That looks almost identical to the Scheme one with the only real difference being foo=bar; vs (foo bar).
Hardly enough of a difference to change anything "a lot" either way.
Guix package definitions were unreadable to me initially, as I had never used Scheme/Lisp before.
I've written a couple of them now and the definition above is extremely easy to read. Big part is just formatting & parentheses, I think my eyes just needed a little bit of adjustment time.