Hexbear started during the 2020 BLM protests, where cops were using social media and internet presence to track down activists. They are still doing this, but with less vigor than when police stations were burning down.
This included things like using tattoos on naked bodies, etsy store receipts etc.
Just before the r/cth ban, there was also a problem with chasers and leering objectification, and steps were taken to reduce thirst-posting and the like.
These things combined means that people don't post selfies or direct identifying information. People post their pets and artwork, but I know I have to make a decision about where and when I post things to make things non-trivial for cops or random chuds. I feel like a unique pet name, breed, and rough region could be enough to track someone down.
Even so, I think I'm bad at it. I feel like if someone knew me and read everything on hexbear they could ID me pretty easily (and I know multiple people in person on hexbear, but we've never exchanged usernames).
Idk if there are any hard and fast rules beyond the selfies and direct ID though. I should burn this account.
Edit: removed reference to masculinity
I think your overall answer on the social side of it was good. Compartmentalizing etc is a good way to think of it. But I feel compelled to challenge any specific technical advise. In general because it's impossible to give advice like this without knowing more details about the recipient. There are ways it could easily backfire by someone just blindly following it.
This plan doesn't really make any sense. The idea of breaking things up by browser doesn't scale like hardly at all. You can only have so many browsers installed on your computer. And they tend to be extremely resource-intensive so you can't be running many instances. A more reasonable way obtaining every benefit possible from this concept would be the use of profiles.
Even ignoring all that, I am still skeptical. Basically the benefit of the dedicated browser/profile concept is that it somewhat compartmentalizes system data which is exchanged with the remote host, ya? Is hexbear.net sharing a lot of cookies with gmail or facebook or cnn or whatever other websites you are going to? Does it make sense to pick 1 special website that will get the special secure treatment while all other browsing is done in.... an insecure environment? Are you opening external links in this special browser or are you copy/pasting them into your general purpose browser? And what about the large amount of fingerprinting that would remain consistent between browsers/profiles, such as IP address and other network infos, system environment, browser settings, session times etc? It doesn't really have much of a hope to accomplish the goal of keeping the accounts discreet.
It also doesn't consider use of mobile devices, apps etc.
Overall this kind of strategy could only even possibly be appropriate if you are considering a very specific adversary, namely one who has insider access to server logs, network traffic etc, of other computers you interact with on the internet. I guess multiple different remote systems in order to triangulate the information. So the owners/operators of servers, or someone who is able to obtain access (like by hacking or a warrant). If you have such an enemy this would hardly be sufficient and it'd be better advice to go straight to TOR. On the other hand, OP seems specifically concerned with "pervy men" who almost certainly do not have such access. It would be better to focus on the social compartmentalization to avoid divulging so much information that some creep can easily compile a dossier on you and track you down.
Setting and maintaining boundaries like that is not easy especially in a comradely social situation. I would avoid adding a bunch of dubiously-useful technically complexities. On the other hand it could possibly help to self-enforce. I like to use browser profiles to segregate off certain tasks. Like I have one for school work. It has a different color theme than my usual one and it reminds me not to wander off into other stuff getting distracted. I am not logged in to anything fun in that browser and I keep all the bookmarks on topic to school. The session can be opened and closed when I decide to start and stop working. It probably has a very minimal benefit in preventing my school-work online ID from getting mixed up with other online activities but I wouldn't rely on it at all. It's mostly just a mental thing.