I run the GUIX system distribution in all my machines - other than the initial install being a bit harder it is great.

Firmware blobs yes. The default GUIX kernel patches out all proprietary blobs, but the nonguix kernel has them. I do have one machine where I also build the kernel package with my own config because the the wifi driver is not build by default in the linux kernel.

Did a quick search here, besides firmware, nonguix has packages for the nonfree nvidia drivers, brother printer driver, unrar.

In addition nonguix also packages software that GUIX does not, e.g. firefox, or third party binaries:

https://gitlab.com/nonguix/nonguix/-/tree/master/nongnu/packages