Question User Interface and Canvas Renderer

So I made a post about this issue and scripting with it, but my issue persists and I'm looking further for help here. I'm setting a mesh to a

CanvasRenderer

that needs a material. I have no idea what kind of material to assign; URP's builtin Lit/Unlit don't work properly, and the Particle/Sprite variations also fall short of working. The closest to working I've got it was the UI/Default shader that isn't even a part of URP (that I'm aware of) and leads to it not disappearing when I disable the GameObject and not showing textures.

So my big question is what do I do when I want to set a material to a UI element? Say I wanted to make a blur shader and set that to a UI Panel... What kind of things do I need to account for, are there any things that I even need to account for?