> I've got a REPL started in Emacs [...] but I'm noticing it > doesn't have such features as more, edit, what, etc.
Sounds like you didn’t load some libraries. When you pass a + character to the interpreter, it loads `debug.l`, which defines (what ...) and other functions. Maybe you can just (load 'debug.l') after the fact, or maybe you need to tell emacs to include the + on the command line when starting the picolisp repl. I hope this helps. Cheers, --Dave