Add tweaks for background colors
Currently, one can only set the image and "adjustment" for desktop and lock screen background. It would be useful if the option for primary color (and maybe also secondary color and gradient type) can be added in Tweaks.
This will be particularly useful since the option for color backgrounds is now gone from Settings in 3.34, and there's apparently no plan to add it back (see gnome-control-center#717 (closed)).