As far as I have tried, at least chatgpt basically cannot do brainfuck. I think it might just be too far from natural language. It basically just gives you hello worlds with randomly injected characters.
https://papers.nips.cc/paper/2021/hash/0cd6a652ed1f7811192db...
(though worse, for complex cases, to one of the compared systems - see figure 2) (oops, fully disclosure: the system in question is my PhD work).