Reuse Shader Pass output as input for next Pass

Hi,

I have been searching for a while, but I have not found much, except GrabPass which I cannot use because I do not have the Pro version.

Basically what I want to do is what it says in the title. I want to render a shader pass and use its output (at least the depth component) as input for the next pass. Is there an alternative to GrabPass, or anything that I can do?

Simply overdrawing the old pass with a blend function won't work for what I need to do.

greetings