It probably doesn't make sense to cram a whole Lisp into a constrained environment like a microcontroller. What some people do instead is define a smaller Lisp which acts as a DSL and is compiled to run on the constrained platform.

https://en.wikipedia.org/wiki/Game_Oriented_Assembly_Lisp is an example of this approach.

"GOAL does not run in an interpreter, but instead is compiled directly into PlayStation 2 machine code to execute. It offers limited facilities for garbage collection, relying extensively on runtime support. It offers dynamic memory allocation primitives designed to make it well-suited to running in constant memory on a video game console. GOAL has extensive support for inlined assembly language code using a special rlet form, allowing programs to freely mix assembly and higher-level constructs within one function."