Here's a tip that will be of interest to Ring camera users. I set up Scrypted on a Raspberry Pi to connect my Ring cameras to HomeKit Secure Video. It works very well:
One feature I discovered afterwards, is that it also let me connect these video feeds to Channels DVR's guide. Once I set the "Rebroadcast Container" to RTSP, a Rebroadcast URL was presented. I copied that, substituting "localhost" with the IP address of the Pi. I then used that URL when setting each up as a Custom Channel in Channels DVR.
tvOS 15.4 now lets you monitor any HomeKit video feed via picture-in-picture but this allows you to integrate the camera feeds individually into Channels' guide interface too, just like other webcams.