• Aegis - two factor authentication

• AntennaPod - podcasts

• Cheogram - xmpp chat, can also handle phone and sms gateways

• F-Droid - technically it can install itself

• Fedilab - my prefered fediverse app for mastodon

• Fennec - basically firefox

• Jerboa - preferred lemmy app

• K-9 Mail - email

• KeePassDX - password management

• Kiwix - offline copies of useful wikis, q&as, archives, etc.

• Lawnchair - alternative home screen / app launcher

• Librera FD - books

• NewPipe - watch youtube videos, although google keeps trying to break it

• ntfy - runs in the background, handles push notifications for some other apps

• Organic Maps - sometimes missing info and it doesn’t have traffic data. simpler than OsmAnd

• Orgzly Revised - note taking. for people not familiar with emacs something like logseq or safe notes might be better

• Pinkt - bookmarks

• Pixelix - pixelfed app. not sure if I like this or PixelDroid better yet

• PocketPaint - make art on your phone

• QuickDict - offline multi-language dictionary

• Syncthing-Fork - syncronize files between devices

• Unexpected Keyboard - has the fancy keys that most android keyboards leave out

• Voice - audiobooks

• WG Tunnel - VPN connection, still not sure if this is the best option

I’ve got hundreds more installed, but those are some of my favorites.

The github page for overleaf seems to indicate the community edition is AGPL.