Looking at ECL, it doesn't seem to have a bare metal port? Or am I missing something? I take it "embedded" in this case means "links with your C code", not "runs on bare metal micro-controller."
Yes, it means that you may link it in your C code or use it standalone (hence – `Embeddable' in name). Lisp programs share ABI with C, so you are able to create library in Common Lisp which will be used from anything having FFI to C ABI.
It does, it's embedded as in "use it inside another program".