Termux. Also, all of these devices (F(x)tec Pro1 X, Planet Gemini/Cosmo/Astro, ...) run a myriad of OSes, so if you don't want to run Android you got alternativ

Termux. Also, all of these devices (F(x)tec Pro1 X, Planet Gemini/Cosmo/Astro, ...) run a myriad of OSes, so if you don't want to run Android you got alternatives (including AOSP-based). As does Nokia N900, just not out of the box back in the days.