>
> Maybe it only works out of the box as described in the manual if you
> happen to be on Guix System but not on Void Linux?

I haven't spent a lot of time with Guix on a foreign distro, but whenver
I have tried it there's been lots of weird problems that I didn't
understand. 

>
> What can I do to debug what the issue is on my system (void linux)
> with geiser?

I'm sure someone who actually knows what they're doing could help more
than me, but my thought would be to start by debugging guile outside of
Geiser. I would try to spin up a repl and see if I could import one of
the modules from ~/guix and check out what the %load-path ends up being.

-- 
Best regards,
Jake Shilling