Question / Help Key and Fill Sources, matt key, is it possible?

[Shilon]

Key and Fill Sources, matt key, is it possible?
like in vmix:

Key/Fill Input
Select another input to use as the Key channel for this input.
The input selected should be grey scale with black representing fully transparent (0) and white as opaque (255).
keying one source by a second source luma values like

 

[cafeWeltschmerz]

I am searching for the same.
I would be able to put key01 online on the active scene with programmable layers in the key (like a TGA stream 32 bit). Or even better: use the fill and key to overlay a selected scene within an active keyer.