How can I use a Post Process Material Custom Depth Mask to mask my UI?

Hi Guys,

I want to have my Character (only) to be on top of the UI, similar to the way it is done in Street Fighter6.

I am using a Post Process Material to mask out my Character using the Custom Depth Channel. The problem I am having is how I can use this Mask to cut out the silhouette of my character from the overlying UI

Thx!