The point of pre-compiling for SBCL, ECL, etc. is that is saves time to the
user.

If you want the source-only Common Lisp library which would work across all
implementations (as long as they are supported), you can install the "cl-"
prefixed package.
Then the Common Lisp compiler invoked by the user will compile the sources into
some FASL somewhere in ~/.cache/common-lisp/... or similar.

Doesn't it suit your needs?

> I'm not certain by what you mean.  I did ask around earlier and learned it's
> not uncommon for Guix to place files in the user's home directory when needed.

I think there was a misunderstanding, Guix cannot modify anything in the user's
home but the Guix profile.

Cheers!

-- 
Pierre Neidhardt
https://ambrevar.xyz/