Clipping 3D material

Godot Version

4.4.1

How to clip an arbitrary material along a plane?

So I created a simple shader material (screenshot) that gets “clipped” by a plane. It uses discards, but setting alpha to 0 would work too.

My question is - I want have any material clipped by this shader! Any textured standard material you could think of - I want to clip it. Is that possible?

I already looked into next passes, and material overlays (same thing?), but they draw on top of the last pass. I need the next one to be transparent if the one below (my shader) is transparent.

Thanks for any pointers