It boots, but some things still don't work:
1) Installation of DTBs
2) Boot of initrd
Booting still needs a proper config.txt in /boot, which could probably be
managed by NixOS.
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.