I don’t have studs on the piece I’m screwing into though. The span is too short and the only studs are in the corners. Weight of the NVR is close to 10 pounds
In this case I would use a thicker piece of plywood on the wall .. spanning from one stud to the other in the corners ..
in the datacom / telecom world they use 3/4" plywood .. I've used thinner ( thinner than 3/4" .. iirc just a bit more or about 1/2" thick ) for my small closet setup ..