On my tablet, I used it as an ssh client.
On my VR headset, I used it to create a self-contained development environment: https://www.reddit.com/r/cyberDeck/comments/fc5sfr/oculus_qu...
You can use its PRoot functionality to run various Linux distros: https://wiki.termux.com/wiki/PRoot
And you can run Linux GUI apps if they are compiled properly: https://github.com/adi1090x/termux-desktop