TV and set top box testing is shared between our partners (manufacturers and operators) and Netflix. Our partners must run our test suite before submitting for certification. We don't have all the devices under active testing all the time, but almost all of the devices have been tested at Netflix at some point. Most operator devices require VPNs to the operator network to function.

So yes, hundreds of devices on a variety of networks, but at any given moment most of the devices are in storage.