@chorist yeah, the uxn emulators that I use are written in C normally. You can see the code here, maybe that'll help you understand. But it could just as well be written in another language. Uxn as a target is rather slow, so for efficiency's sake, it's best if some drawing calls and memory management is kept in near native scale.
https://git.sr.ht/~rabbits/porporo/tree/main/item/src/porporo.c