Other solution i tought worked didnt end up working after all … so here is what actually worked:
systemd.user.services.set-wallpaper = {
description = "Set KDE Plasma wallpaper";
serviceConfig.ExecStart = [ "/run/current-system/sw/bin/plasma-apply-wallpaperimage /etc/nixos/other/wallpaper.png" ];
wantedBy = [ "graphical-session.target" ];
};
I put this in my configuration.nix (I had to us absolute path as it wouldnt recongnize the command otherwise) Any improvements appreceated ^^