Is there any difference between the native shell and Termux’s? I just installed fish and chsh’ed it to default: after syncing over all my dotfiles it looks and acts as expected.

I did the same, but that’s not what I’m talking about.

I don’t know for sure, but if I hat to guess I’d say that Termux uses chroot to emulate a more Linuxy experience by changing your root to /data/data/com.termux/files/ with it’s own bin, etc, lib and so on directories

Using su you escape that chroot and start using your roms root directory at /

I might be totally wrong with this, but that should hopefully clarify the way it behaves