Depends what you mean by "Linux" here.
It's probably not the kernel itself, so do you mean
- a terminal e.g. a working shell where you can run commands e.g.
ls | wc -l
? - headless containers, e.g. services like Immich accessed elsewhere?
- a window manager e.g. KDE or Gnome?
- a software with a visual interface, or GUI, e.g. GCompris?
Based on that then one can answer if Termux is sufficient (or "legitimate") or if something else is needed.
PS: You can read some of my notes on termux on different Android devices at https://fabien.benetou.fr/Tools/Android