Android
Mobilism - https://forum.mobilism.org/viewforum.php?f=398
Mods.
4PDA - https://4pda.to/forum/index.php?showforum=212
F-Droid - https://f-droid.org/
APKMirror - https://www.apkmirror.com/
Apps
foobar2000 - https://www.foobar2000.org/android
Music player.
eBoox - Google Play
Reader for EPUBs.
Pocketbook - Google Play
Reader for PDFs and DJVUs.
Home Dictionary - https://github.com/mortalis13/HomeDictionary/releases
Great app for .dsl dictionaries.
Feeder - Google Play
Open source RSS reader.
YouTube Revanced - https://github.com/MentalBlank/YouTube-Revanced/releases
YouTube without ads and Shorts.
Smart AudioBook Player - Mobilism
Good audiobook player.
AntenaPod - Google Play
Open source podcast app.
LibreTorrent - https://github.com/proninyaroslav/libretorrent/releases
Open source Bittorent client.
Firefox - Google Play
Don’t use Google Chrome. Google went full totalitarianism removing uBlock. Firefox Android app can install same extensions as desktop browser. Firefox is the GOAT.