EDIT: Shader Graph File is added to this post! And I made a Youtube Video about it too, still getting used to editing so it's a bit rough, will get better in time :>
EDIT2: Added Shader Graph version that lets you keep black outlines
Very simple shader, but one I haven't shared yet (Though there is a similar one for surface shaders, not sprites/UI in the tutorial list). I made this for the Cat-themed Twitch overlay for my stream.
Shader Code: https://pastebin.com/U7twRcnf
There's an option to leave black pixels untouched, for outlines.
I've added stencil support, so it will work with UI masks if needed!
The concept behind this shader is to swap out color channels for customisable colors. A use case is a player color emblem, or armor sets that can be dyed in a 2D game :)