Ideally I'd reach ANSI compliance, first with a bytecode compiler and then with a full one

Is there some important shortcoming of all the existing Common Lisp implementations that you would like to correct?

Awaiting answers. Seems stepping is one.

Btw, I stick to sbcl as I used vim and so far the script here works for me. Might try this when back to do lisp.

https://susam.net/lisp-in-vim.html

Yeah, advanced debugging features like watchpoints are very important to me