What is your favourite/ most used FOSS android apps?

to name a few I like:

• Read You, brilliant RSS reader. Now syncs with Freshrss. Inspired by Reeder on iOS
• Voice, audiobook player. I use it in fact to listen to audio from youtube videos (downloaded with Newpipe). For audiobooks (and podcasts) I use
• Audiobookshelf (needs server)
• FUTO keyboard with decent on device voice recognition! (exists as a standalone)
• 8Vim, weird keyboard I really like
• Fairemail has been my trusty email client for years. Don't be spooked by its many options, once accounts configured the UI doesnt show unecessary stuff IMO. Some unique and useful features.
  But if you want something simpler there's K9, now Thunderbird. Although I still experience the issue with emails not arriving on time with this newer version
• KeepassDX, great password manager, good UI, keeps improving.