What does it do? “Like android has” isn’t very descriptive :D

because its not about jit per se, its about marking pages of memory as executable. doesn’t matter whether you compile it or load it from disk, you need to mark the memory as executable so the cpu will run it, and that isnt something “normal” ios apps are allowed to do.

Okay but would you prefer the alternative where anything with root permissions (either apps with privileged helper processes or any pkg you ever installed) can modify the OS in whatever way it likes and permanently and invisibly install some kind of malware/spyware?