Let's say I'm working on a project that requires Go, Node, maybe some C library, and GNU Make. Seems like I would be able to use guix shell for this, right? Great.

Iirc guix shell is for one off package or programs you want to test, say you want to quickly format a drive to exfat or so, when you exit the sub-shell, the installed packages are discarded

guix shell containers would work best for your scenario but I have little experience with them