If you mean the servers you could use something open source like bitwarden and just not use their online service, you can host your own server or use it locally.

Have you tried looking on itch.io? I recently got a few games from there (some are hosted on the play store but not all)

Only bad thing about browsing is that 80% of the games seem to be dating sims or visual novels (which is fine if you’re looking for that, but annoying if you’re not)

Edit: infidhells seems really fun, but haven’t had time to play much, to use all the gameplay features it’s worth playing with the sound on (though it has accessibility options for playing without audio).

The game isn’t even out yet and people are excited for mods that will fix bugs. JFC there’s a reason AAA games these days launch incredibly broken