If you want to have a REPL on something like a microcontroller, there's a tool designed especially for that: Forth. You're going to find an implementation for any chip and platform you can think of (Forth is 40 years old and simple enough to be trivially portable to almost anything). Forth is strange and feels archaic at first, but I'd say it's roughly on par with Lisp in terms of expressivity and much better suited for systems with constrained resources than Python.