Suggestion: instead of adding one phase per wrapper, use a single phase,
loop over the executables to generate the wrapper.  This should shorten
your code.

I think the "gi" issue is because "(getenv ...)" does not include the
output "out".  I'm guessing you need to add (string-append out
"/lib/python...blueman...") to the PYTHONPATH.

Cheers!

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