Yes, I've done almost exactly this while traveling. You can even carry around a couple variously configured sd cards for different use cases. I had one with jellyfin for sharing locally and also Kodi for direct HDMI connection to TVs. There is a in app on Android for jellyfin called findroid that allows offline copies from the media server, which allowed me to not need the thing powered the entire time I wanted to watch something on my phone, just long enough to download it. Adding samba shares adds a other layer of accessibility. I had another SD Card with video game ROMs for retro gaming, but this one got left at home because it requires controllers and I didn't think I'd use it that much. I had another with "little backup box" installed for automatically backing up my photos and videos after a day out exploring with my camera.
I used a Raspberry pi 5 for all of this, running from a battery backup, because I didn't really need a keyboard once I had remote connections to my phone sorted out. Pick a rugged case and you case just toss it in your bag of chargers. It took up about as much space as a pack of cigarettes. Another option would be the Raspberry Pi 400, built into a keyboard. A little bulkier, but maybe more resilient in the face of technical difficulties.
It's not a full monopoly. You can choose another ISP, but it's just that in practice you'd need to physically move to a new location to make that change of vendor.