In a similar line as the posted project TinyLisp, I'd like to mention uLisp.

Lisp for microcontrollers - Arduino, Adafruit M0/M4, Micro:bit, ESP8266/32, RISC-V, and Teensy 4.x boards - http://www.ulisp.com/

In particular, its smallest variant (~800 LoC).

> uLisp Zero is a pared-down version of uLisp, capable of running in 8 Kbytes of program memory with 1 Kbyte of RAM

https://github.com/technoblogy/ulisp-zero/blob/master/uLispZ...

---

And I can't help but mention Make-a-Lisp and its C implementation (~350 lines).

https://github.com/kanaka/mal/blob/master/impls/c/stepA_mal....