Termux is my lifeline to my main Emacs session. Besides ssh and small scripts I also run a couple of personalized services in it that I've written in Go.
Antennapod listened to thousands of hours of podcasts in it
Fedilab is my favorite mobile Mastodon client. I also use Jerboa for Lemmy but it's not quite at the favorite app level yet
KeyMapper is essential for me, especially when managing a physical keyboard
NewPipe for youtube
Shattered Pixel Dungeon roguelike dungeon crawler
MuPDF sensible PDF viewer
Also, RIP RedReader I know it still works but I've moved on from reddit.
If you are in this post you should definitely know about F-Droid, and if you don't... well, welcome to where open source apps are FOSSly distributed, and some paid apps on the Play Store like Fedilab and OsmAnd are completely free, both as beer and freedom.
Then, you can pay those 2.7$ directly to the developer (if you want) instead of giving part of it to Google.
I strongly recommend you install the Neo Store for a very modern frontend for F-Droid.
For extra coolness, activate the IzzyOnDroid repo on Neo Store for getting way more FOSS apps to download with quicker updates.