If you have a mostly Gnome system then you can make sure to run these lines when you login:

dconf write /org/gnome/desktop/interface/color-scheme "'prefer-dark'"
dconf write /org/gnome/desktop/interface/gtk-theme "'Adwaita-dark'"

I have two simple shell scripts, prefer-light and prefer-dark that I run when I want to switch:

❯ cat $(which prefer-dark)
#!/nix/store/xy4jjgw87sbgwylm5kn047d9gkbhsr9x-bash-5.2p37/bin/bash

dconf write /org/gnome/desktop/interface/color-scheme "'prefer-dark'"
dconf write /org/gnome/desktop/interface/gtk-theme "'Adwaita-dark'"

❯ cat $(which prefer-light)
#!/nix/store/xy4jjgw87sbgwylm5kn047d9gkbhsr9x-bash-5.2p37/bin/bash

dconf write /org/gnome/desktop/interface/color-scheme "'prefer-light'"
dconf write /org/gnome/desktop/interface/gtk-theme "'Adwaita'"

If you want to go deeper and also affect Qt applications and such, then you can always look at the Home Manager source code to see the files that it writes when you follow the tutorials.

You don’t seem to actually use inputs in your home.nix file so in principle you should be able to remove the

home-manager.extraSpecialArgs = { inherit inputs; };

line. Doesn’t hurt to keep it, though, if you think you may use inputs in the future.

The change you propose in 3 would not work the way you expect, the extraSpecialArgs needs to be set for Home Manager, not NixOS. My guess is that the nixosSystem function simply would ignore the extraSpecialArgs parameter.

Agree that there doesn’t seem to be anything weird here, the only suggestion I can add is that you could make it a bit more idiomatic by changing

home-manager.users.bs = import ./hosts/default/home.nix;

to

home-manager.users.bs.imports = [ ./hosts/default/home.nix ];

For many years now whenever I travel within EU I use my EU identity card and it’s very convenient. Would indeed be great if I could use something like it outside EU as well.

Great job!

OVPN has been RAM only for a long time as well, the describe it on their website.

I’m pretty sure it is not her personal responsibility to solve the climate crisis on the behalf of the rest of humanity. That would probably be best left to various subject matter experts, which I believe she has said many times.