Does the NUC support hardware acceleration? Otherwise you could just use a Pi 4 for this and run all your cameras through gstreamer, which supports the ops you

Does the NUC support hardware acceleration? Otherwise you could just use a Pi 4 for this and run all your cameras through gstreamer, which supports the ops you want - I think you can even do PiP. One thing I don't know though, are you going to have to decode the streams, overlay and then encode again? You could also look at getting a Jetson Nano which is a bit beefier, and you can offload some of this stuff onto CUDA. Easy to try the opencv route, but you need to be a bit careful on ARM (make sure you compile yourself with all the optimisation flags on).