Hi!

This is a small shader, based on the original from unity, that you can pick a color (255,0,255 for example) 

and it makes that color tranparent. I think it can help the development for some one =)

https://gitlab.com/snippets/1962225

complete project:

https://gitlab.com/z3r0_th/paint-jam-2020

Dude this is litttttt

Remember that you probably want the sprite in Unity3D to be "Filter Mode = Bilinear" and no compression. Also, remove anti-aliasing.