Avoid anything that requires its own app, Internet access, or mentions "cloud" in any way. AFAIK plain old "dumb" IP cameras with widely compatible HTTP/RTSP streams are still available.
Ironically, you used to be able to just Google for publicly accessible IP cameras, https://news.ycombinator.com/item?id=5116676 , and those don't need anything more than a browser to view, so that might guide your buying decision.
Fwiw I don't use the app, but I have a Yi 4k camera, which I bought used as a cheap GoPro alternative, and it's surprisingly easy to hack some stuff with.
It has a WiFi connection feature which is primarily meant for use with their app (which is kind of garbage), but it's a Linux system and I can telnet into it with root privileges and mess around with the filesystem. It has an rtsp stream, a fairly ok remote control API with some community libraries in github, and even has Python (2.7, at least until I take the time to figure out how to cross-compile a more recent version, but still).
Just this week I was playing with building a script to hook up the rtsp stream to my PC so I could use an AI model to do bird classification and set it up next to my bird feeder.
It's not advertised as being hacker friendly and I imagine this openness is more due to a lack of the zealousness and resources that more expensive products seem to insist on dedicating to locking everything down, but it's been really fun and I'd definitely get a couple more cheap ones, given the opportunity. No idea what the situation is on their other products though, and it does suck that non-technical users are stuck with an app with ads.
Ironically, you used to be able to just Google for publicly accessible IP cameras, https://news.ycombinator.com/item?id=5116676 , and those don't need anything more than a browser to view, so that might guide your buying decision.