Building a Lisp OS from Scratch?

I was inspired by the story of how Serenity OS was built and I'd like to similarly build a basic OS (similar to xv6) using lisp as a way to both learn about computers and lisp programming. I haven't decided yet on a good lisp dialect to use. I'd like to build it on top of a RISC-V architecture set. I'll start with the bootstrap process and see where I can take it from there. Any suggestions or tips?