Joplin : Notes
Macrodroid : mostly to keep my files tidy. Way back in the day of SD cards in phones it helped transfer things over nightly in preparation for my sync job with...
Syncthing : Magical and finicky software
Loop Habit Tracker : Notification pops up, "Did you exercise today?" You answer yes or no and it logs it. I have several questions throughout my day, one of which being how I felt for the day. It's interesting to go back and see which habits improve my day.
Tasks.org (app) : simple to-do app
RaspController : manage local raspberry pis
Wireguard : Selfhost a VPN to "remote" into my home network
Quickimgur : this one is hard to find now. Adds a simple option to the "Share" button on photos. It uploads to imgur and copies the link to my clipboard. No account required.
Aurora Droid : A nice skin for F Droid
YouTube Vanced : Removes YT ads and enables background play. Also restores dislikes and works with Sponsorblock
Privacy.com (app) : Let's you spin up temporary credit card numbers when purchasing things online.
Zone Launcher : shortcut launcher. I swipe from the bottom right of my screen from anywhere on my phone and release over the app I want to launch.
Probably others but I don't even know if these are "special". Just some of my first downloads on a new phone.