I've been down the rabbit hole and I'm starting to get an idea of how this comes together (I think).
I'm considering picking up something like this 4K 120Hz HDMI 2.1 Splitter from EZCOO. The splitter device is responsible for the image I see on the TV, therefore this is what needs to be compatible with 4K resolution, 120Hz refresh rates, CEC, viewing DRM content, Dolby vision, etc.
The grabber (or capture card) does not require any of this. If it is only 1080p 30hz it will not change the image I see on the TV. It simply grabs the image on the TV to mirror colors in the program which tells the lights what color to be. I'm considering this grabber.
Am I on the right track with this? Thank you for the support.