HDRP DepthMask Possible?

Hey there!

I've been banging my head against this for a while but I cannot figure out if it is possible to create a DepthMask shader for HDRP (as descibed here).

For my exact use, I'm trying to create a "hole" in the shape of whatever I have the material applied to, that shows the contents of a different camera rendered behind everything.

I tried messing around with the render queue within the shader, different ZTest and ZWrite combinations, as well as some variations of the shader I found. On top of that, I tried messing around with every configuration of the base HDRP shaders I could think of that might do something.

The closest I could get was making transparent materials behind the object vanish. This does mean that if I set all my Opaque materials to Transparent I get the effect I desire, however this isn't ideal, as it breaks more than it solves. Ideally, I'd be able to somehow use the HDRP transparent priority system on Opaque materials, but am not sure it's possible.

I'm not quite sure what to try next, any assistance would be greatly appreciated!