Allow option for standard non-steam deck branch

[anthr76]

Hello! I've been consuming and using Jovian-NixOS very well for a general purpose x86 living room console. Though, I did want to try the non-steam deck branch of steam as I understand SteamOS should be near feature parity in big picture mode.

My reason being is because the store looks a bit off blown up on a 4K TV and subtle quirks in the settings assume a steam deck.

I've tried poking through the plumbing and I assume this line in gamescope-session would need to be configurable:

steamargs=("-steamos3" "-steampal" "-steamdeck" "-gamepadui")

I understand I can alternatively build essentially what Jovian does and use upstream nixpkgs but Jovian has lots of batteries included, even for non-deck hardware.

[samueldr]

The options added in #259 allows changing the environment (and less environment) bits of the gamescope-session script.

It injects the environment affordance after steamargs is defined

Jovian-NixOS/pkgs/gamescope-session/0001-gamescope-session-Add-xdg-environment-overrides.patch

Lines 16 to 22 in c11bab1

	short_session_count_before_reset=3
	SECONDS=0
	+# Jovian NixOS environment overrides hook
	+if test -e /etc/xdg/gamescope-session/environment; then
	+ . /etc/xdg/gamescope-session/environment;
	+fi

See also:

• https://github.com/Jovian-Experiments/PKGBUILDs-mirror/blob/92e7fe11493915a23745e96e78ecac87af0c1a02/gamescope-session#L335-L347

While you can't use the jovian.steam.environment option directly

• Jovian-NixOS/modules/steam/environment.nix

  Lines 18 to 19 in c11bab1

  	jovian.steam = {
  	environment = mkOption {

You can add to the text file it's creating

• Jovian-NixOS/modules/steam/environment.nix

  Lines 31 to 32 in c11bab1

  	environment.etc."xdg/gamescope-session/environment" = {
  	text = concatStringsSep "\n" (

Since its type allows it.

This should be sufficient to unstick yourself for experimenting and testing, and if it ends-up showing it might be helpful to "own" the steamargs value from within Jovian NixOS options, then we'll be able to.