I have a work-in-progress called Modus. 100% written by Claude, so take that however you will. The current release boots on a Raspberry Pi Zero 2 W. The next release (unreleased in the pipe for ~ months) is standard Common Lisp on bare aarch64 (pi) and x64 (qemu for now), with linux aarch64 and x64 command line interfaces à la sbcl.

https://github.com/modus-lisp/modus

Since you can't use an OS by itself, I've rounded out the Common Lisp environment with portable ssh client and server, web browser, and a bitcoin node. Framebuffer with VNC in the pipe