Pacman has pacman -F filename and pacman -Qo to search files in the repository and installed packages.
Does shepherd have something similar?
Shepherd is an init system, so it does not. But guix has the guix locate command, that works for finding any file within a package.
Unfortunately, it’s not as “powerful” as the equivalent feature in other package managers, just yet, as it just locates files in locally available packages (read: packages already in /gnu/store). And it is rather slow. Hopefully it will be able to locate files in entire channels in the future, but not right now.