Yes, Game Capture has the “Transparency” property which allows adding a source that uses alpha channels (like veadotube or some emulators like retroarch) and automatically removes the background marked as such.

It is different from adding a chroma key, since adding that sacrifices a color and it might clash with whatever the source (like an emulator) displays or if you add something with some sort of “faded” opacity, it mixes with the background color and looks bad.

Game capture

OBS Studio lacks some options on Linux