Anyways, here are some of my favorites (in no particular order):

- Ventoid: Prepare Ventoy USBs from Android

- Termux: Android terminal app and Linux runtime environment (you can run full Linux DEs like XFCE or even play Windows games via Wine!)

- IronFox: Possibly the best anti-fingerprinting browser for Android

- Thunderbird (K-9 Mail): No need to explain this

- NewPipe: Ad-free YouTube client / downloader with background playback

- Hacki: Hacker News client

- Nunti: Smart RSS reader

- Flare: Mastodon, Bluesky, Nostr, RSS client

- Nightzuku: Updated fork of Shizuku, which provides root-like functionality without root

- Unexpected Keyboard: Modern replacement for Hacker's Keyboard

- Element X: Video calls, chat etc over Matrix

- MPV: Lightweight media player

- Mullvad VPN: Possibly the best privacy-respecting VPN

- KeePassDX: Possibly the best password manager (and it's NOT written in Javascript!)

- WiFiAnalyzer: WiFi channel optimiser, signal strength detecter

- NetGuard: Firewall

- Aurora Store: FOSS Play Store frontend, for the rare ocassion you need to download something from the Play Store but don't want to touch the official app

- Obtanium: Android app updates for apps not on F-Droid