Clarification on git packages (mesa-git and linux-mainline)

I am on arch I am planning to switch soon to nix
basically I am on an encrypted btrfs with a bunch of subvolumes so all I need to do is format the root subvolume and install nix there hopefully that’s all I need to do

anyway so in my setup I need (want mosly) to have linux-mainline and mesa-git specifically the nouveau-experimental build options for NVK — The Mesa 3D Graphics Library latest documentation
is that possible without the need to rebuild my entire system
also I have a custom udev rules and custom alsa profile is that also possible to configure
just checking since well testing merge requests and patches is fairly easy on arch and I don’t want my setup to be impossible on nix
so yeah asking people before making the jump

I cannot answer for the mainline linux and mesa-git, but with how NixOS is designed it shouldn’t be too complicated.

For custom udev rules the services.udev.extraRules option can be used to easily add custom rules.

sound.extraConfig looks like it may configure alsa. will be your friend for this stuff.