Here’s what I’m currently doing for my Reolink cameras:

I use an PI 4 with Motion Eye OS (Discontinued, but still kinda works, there is betas of an attempt to bring MotionEye back) to convert the RTSP streams to Web streams. Then using MMM-EmbedURL, I’m able to pick up the web streams to use on my mirror.

What I’d like to do is use something faster and more reliable - (Scrypted?) to do the conversion. Currently, there’s a lag that will form within the motioneye software, so I tend to reboot the pi once an hour (overdone, but it works) to keep it reasonable.

If I use the Framed version of the URLs that MotionEyeOS provides me (like http://192.168.0.7/picture/2/frame/) - I don’t have to have MMM-Embed URL reset the picture, the system will provide a temporary “No Camera” image while it’s down.+

Important note: Pi 5 (and newer, eventually) will NOT run what’s required for the old software, so Pi4 is what’s recommended.