I don't have a John Oliver video, but I do have this https://xinjiangahr.carrd.co/ which is a collection of well-researched data on the subject, gathered up in an easily approachable and surveyable format

Sources on East Turkestan project:

https://www.fmprc.gov.cn/eng/zxxx_662805/202205/t20220507_10683090.html (Chinese source which cites its references)
https://www.cfr.org/backgrounder/east-turkestan-islamic-movement-etim (Pro US/CIA source that shows you what the Western narrative is)
https://www.aph.gov.au/DocumentStore.ashx?id=4767d3ce-8490-464f-8508-d8f3b7878808&subId=703775 (PDF of Australian minister's analysis of the situation submitted to Australian parliament to oppose sanctions)
https://en.wikipedia.org/wiki/East_Turkistan_Government-in-Exile (note that the East Turkestan Govt in Exile was formed in Washington DC and operates out of Washington DC)
https://en.wikipedia.org/wiki/Turkistan_Islamic_Party (note that the US has listed this extremist party as having "training and financial assistance" from Al-Qaeda and ...)
https://en.wikipedia.org/wiki/Hasan_Mahsum (But the party was founded by in 1940 and associated with Islamic extremists fighting the USSR, which we know the US funded and trained)
https://apnews.com/article/79d6a427b26f4eeab226571956dd256e (AP article about how Uighur's are fighting against Assad in Syria after being trained by Al-Qaeda)
https://www.politico.com/newsletters/national-security-daily/2021/10/05/bidens-era-of-strategic-competition-494588 (politico short blurb about how the Taliban is cooperating with China to remove East Turkestan militants from the Chinese border now that the US has left the region)
https://www.ned.org/testimony-by-damon-wilson-before-senate-foreign-relations-committee-on-democracy-and-human-rights-us-tools-and-responses/ (NED, the CIA's "legal" arm, states they support Uyghur partners)
http://english.scio.gov.cn/xinjiangfocus/2020-03/05/content_77241200.htm (Chinese article, but really well done history. If you don't believe the CIA/Dalai Lama connection, just read his brother's book)

https://asiatimes.com/2021/04/why-xinjiang-is-central-to-us-cold-war-on-china/ (Great article by Vijay Prashad on the strategy without the accusations of direct CIA training)
https://www.newsclick.in/the-US-trying-light-match-islamic-extremism-china-xinjiang (Another great article about the origins of US-led jihad and the origins of Uyghur extermism)
https://www.youtube.com/watch?v=nB9HRKKZHak (Interview with Vijay Prashad about the topic)
https://ndupress.ndu.edu/Portals/68/Documents/stratperspective/inss/strategic-perspectives-42.pdf (Page 16 centers the jihadist terrorism in the region that extends from the 80s into today and is recognized by US academia and military)

Like it might be tending towards cultural genocide

Still no. What the US is doing to the native population is cultural genocide. Xinjiang is a legally protected autonomous region explicitly to prevent assimilation as a requirement to engage in society. They teach and speak their native language in school, they conduct commercial and government business in their native language. China is running the most complex multi-cultural society in the history of the world. They are not engaged in cultural genocide.

through not letting them wear their clothes or practice their religion or culture

There are more mosques per capita in Xinjiang than anywhere in the world. The clothes and practices you're talking about are explicitly East Turkistan separatists, a movement with no basis in history that was fomented by the CIA in a radicalization program, the existence of which is public knowledge, with the explicit purpose of destabilizing China, just like the CIA used to train Tibetan terrorists and then airlift them into Tibet.

As for it all just being Zenz’s word, what about the satellite pictures of their massive camps and their growth, videos and pictures of their re-education schools (think I saw this on the Jon Oliver episode of the subject?), Xi’s 2017 order that all religions have to be Chinese in nature, and some Uyghur saying they had family members arrested and now don’t know where they are, like Ilham Tohti.

Since the days of the Mujahideen, the US and British military intelligence agencies have been developing a perverted interpretation of Islam for the purpose of creating religious extremists, training them in guerilla warfare, and aiming them at countries they want to control. The Uyghur's of Xinjiang are the target of the CIA East Turkistan radicalization program. The satellite pictures do not actually show anything like what would constitute even a human rights violation let alone a genocide. Prisons and re-education are literally the response to the radicalization program. The number of terrorist attacks in Xinjiang plummeted through this program, and instead of vilifying Islam, like the West does, the autonomous region is still autonomous. Xi's order that all religions must not call for the destruction of the Chinese state is pretty straightforward. If the USA is inventing a history of East Turkistan and wrapping a religious fervor around the project to separate from China and create an independent Islamic state, then the solution is to establish that Islam is just fine, but religious justification for terrorism and separatism remove the protection from the state that all religions have. Thus, Xinjiang is still massively Muslim and the state is allowed to arrest extremists who justify their extremism with a perverted interpretation of Islam and they get reeducated IN ISLAM to show the contradictions in their position. They are reeducated away from the radicalization programs of the CIA and MI6.

but it comes off as the Islamophobic version of the WW2 Japanese-American internment camps where innocent are thrown in with the guilty

Stop projecting Western racist atrocities on the rest of the world. Chinese people were exposed to the worst excesses of European racism. They are steeped in that history. They have zero desire to repeat it. They are not rounding up everyone who looks Muslim. They are, however, likely catching some innocent people in their efforts to stop attacks at the root. On balance, since they aren't harming these people, but rather establishing a process by which they can be sure they are deradicalizing as many people as they can, I think we can agree that it's better than the dragnet the USA implemented after 9/11 and the number of innocent people they kidnapped, tortured, and put in secret prisons in other countries and left them to rot or die.

Why else would they need to be that big?

Do you have any idea how big Xinjiang is? How many people are in ISIS or Al Qaeda? Would you rather the prisons actually be small fenced in yards with people packed in like sardines? Or should the facilities for these people be large, spacious, and accommodating? Maybe you can't imagine China imprisoning people and treating them well because the US treats pregnant women like dogs by packing 4 of them into a single cell or because they put toddlers in solitary confinement. But the PLA won the war because they showed the KMT soldiers that they were far more humane, far more thoughtful, and far more just than the KMT was. That history doesn't die easily.

And not letting people see the prisoners like that guy I linked above isn’t great either

China has no obligation, while fighting a Western radicalization program, to let Westerns inspect their operations. Beyond the possible ways that could be used to inoculate new radicalization targets against reeducation, the West has zero moral standing and cannot set these terms and China is letting them know they have no grounds to impose terms on how China fixes a mess the West created.

especially since the people defending it are usually the same people criticizing the US’s massive prison industrial complex, although I sometimes confuse the views of ML communists, who might be okay with that if they were used on the right people, and anarchists, who I know are definitely not.

Anarchists don't support China, so that's easy. Listen, the US imprisons so many people that even with massive prisons in Xinjiang China's prison population per capita still doesn't even come close to the US's. The US also has a massive extractivist parole system so you can't even count just the people in prison you also have to count all the people with ankle bracelets AND all the people with $50k in debt to the prison that garnish their meager wages for the rest of their life. You are projecting Western atrocities onto China and then getting confused why people who criticize American atrocities also support China. It's because you are imagining Western atrocities are equivalently happening in China when they aren't.

China is allowed to be distrustful of the West, but I don’t think that trumps human rights.

China is distrustful of the West because the West is the worst offender against human rights the world has ever seen, and a lot of those human rights atrocities happened under Western occupation of Asia.