Fill a PNG / Alpha Video with a color (like cliping mask)

Hi everyone.

I'm currently trying to switch from After Effects to Fusion.

And now, I'm trying to find a way, to fill my PNG Sequence with a color like the tool "Fill" in After Effects.
I tried during 3 hours this morning to find a way without success..

Is anyone has a solution ?

I'm on Davinci Resolve 17.

Thnaks in advance.

I think the easiest way to do this would be to pipe your png-sequence into the maskinput of a background-node (aka a solid in AE)