Went to double-check both things.

About root, I think I got it confused with two different things at the same time, termux-setup-storage, and the external storage specifically requiring root to work (first paragraph after the data table).

About (not) being a Linux distro, reading deeper into it, it sounds a lot like DOSBox, which is also a terminal emulator which can run programs for the system it pretends to be while using the host system's file system.