> Actually I find it normal that ASDF has no .asd file [...] I am new to Guix, so I'm not sure what's considered "normal" here.
Guix is the only package manager I know that does not include an .asd file for ASDF. Nix's asdf includes an asd file. Debian and Ubuntu's cl-asdf includes an asd file. FreeBSD's cl-asdf includes an asd file. The upstream includes an asd file ...