This change sets the wallpaper to one with a NixOS brand.

What other distributions have done is make a new branding theme and set it as the default. Maybe we should follow them as soon as the panel/theme issue is fixed.

I am not sure about committing this change and would like to see other opinions.
cc @worldofpeace @jtojnar

Yes, setting a branded wallpaper is an opinionated decision.
The current default points at a non-existent wallpaper, sets a black background. Together with the default panel background, this is a bad UX.
Fixing the wallpaper is easy and a quick win, while the panel/theme issue linger around for some more time, I suspect.
Regarding the branded wallpaper, I was inspired by #86163 but I favour the blue wallpaper.

ping @worldofpeace @jtojnar

I am not sure apps should depend on system theme. Is there a way to set the background in a NixOS module rather than pcmanfm?

I updated the PR to just fix the path instead of using NixOS-artwork.
The main problem was that the template config is copied to user's home at first login, and without this change the Wallpaper would be set to a file in the Nix Store that is eventually GC'd (due to the hardcoded path). Now using the proper symlink from /run/current-system/sw....

@jtojnar Ok for you?

ping @romildo @jtojnar @worldofpeace

Looks like that should work, at least in LxQt.

The path is linked:

I am not a fan of using this nexus but I guess it is fine until #47173 is resolved.

This is currently imho the best (and only without further indirection and hackery) way to have a stable path that always points to the currently active lxqt-themes package.

Also fixed a missing slash in this path.

There are 3 commits. Reduce them to just one. Then I think it will be ready for merging.

Yes. That was meant for easier review. Should be good for merging now.