Been using NoPhoneSpam. While it won’t automatically block any numbers, it will cancel incoming calls not matching its filters. Only issue is that, some times, it takes a few seconds for it to recognize not passing calls, but I think it happens when the phone is under a higher load and the system starts lagging a bit, like when downloading bigger files and playing games.

Look for games that are sold DRM free. Those can’t be taken from you by devs or the store after backed up. And usually devs and/or stores that deliberately sell such games also make it clear people can keep their games.

Maybe this helps?

https://addons.mozilla.org/en-US/firefox/addon/single-file/

I use it on PC, and from what I just tested on my phone, it seems to work fine.