A few FOSS that I havent yet seen mentioned (assuming everyone already uses AntennaPod, Aegis, Keepass2Android, OsmAnd, Signal, VLC, SD Maid SE etc):
- FairEmail - Email client
- Voyager - Lemmy client
- whoBIRD - Shazam for birds
- Subz - Subscription manager/notifier
- Untracker - Remove tracking info before sharing links (YouTube, Amazon etc)
- Obtainium - Update manager/notifier
- PDF Converter - .pdf tool. May be abandoned but doesnt require internet & is useful
- MJ PDF - .pdf reader
- FitoTrack - Fitness tracker
- Shelter - Work profile for if your employer won't provide a work phone but insists you use a shitty 3rd party proprietary app for everything from booking leave to payslips to health scheme to... Well anything, coz everything has to have its own shitty app these days, right?
I tried Hoarder (KaraKeep) & Linkwarden. Both excellent but I preferred the UI for Linkwarden, particularly on mobile, so I stuck with that - i found Hoarder awkward to edit thumbnails for example though things may have changed in KaraKeep. From Android perspective both have apps but I prefer to use browser plugin. With Linkwarden there's some hoops to jump through on Android Firefox but it works perfectly once set up. Both excellent choices.