iSH and a-shell offer some (emulated, non-JIT) Linux CLI functionality on iPad, which is quite functional for compiled apps, e.g. taskwarrior.

Yes, I've played around with a-shell but I consider it more of a toy than a tool. It's honestly kind of weird that Apple allows it.

Supposedly JIT is possible [1] for sideloaded apps, including UTM (QEMU). Apple does have the power to re-enable the hypervisor API in iOS at any time, perhaps after Google unifies Android+ChromeOS, including Debian Linux "developer" terminal VM. At least these emulation and JIT hacks let developers explore use cases for non-appstore software.

[1] https://onejailbreak.com/blog/stikdebug-ios/