As zelphirkalt pointed out, one project I use with guix shell is named Chickadee. It's a little game dev library.

Here is the guix.scm file: https://git.dthompson.us/chickadee.git/tree/guix.scm

Here is another project (a static site generator) with a much simpler guix.scm file: https://git.dthompson.us/haunt.git/tree/guix.scm

In both cases, this same file can be used to create a development environment via 'guix shell', build from scratch in an isolated environment (handy to run before a release) via 'guix build', and it can even be installed with 'guix package'. It's super handy.

I was looking for an example as well, when I saw the nickname of the GP. He created a nice project named Chikadee and the source code can be seen at https://git.dthompson.us/chickadee.git/tree/, where you can also find the guix.scm file.