This one is problematic: for the package to work the user has to define

export GI_TYPELIB_PATH=~/.guix-profile/lib/girepository-1.0

and

export LD_LIBRARY_PATH=~/.guix-profile/lib

The former is required to instruct 'gobject-introspection' where to
find typelib files and should be fine, but I'm not sure how to display
a message telling this at the end of the installation.

The latter is a hack. As discussed on another thread, the typelib
files have references to dynamic libraries and they do not include the
full path.  We are looking into a patch to add the full path into the
typelib files, however, the patch only works on newer versions of
'gobject-introspection' which breaks several other packages.

Setting this environment variable should be a temporary solution.

Regards,
Fede