I have an 8 wireless IP camera system with NVR on a closed network. That way I can use closer ones as repeaters for the ones further away and view them on my phone simply by connecting to the closed network but they can never 'phone home'. Updates are air gapped via a USB fob. 1tb drive keeps about 28 days rolling history. A couple of the cameras are PTZ and one has a mic. It could probably be hacked locally but they'd have to be on my property to do it since the Wi-Fi coverage doesn't extend to the property boundaries. The software is, like you said, is a bit Chinese but full featured with motion zones, multiple time window scheduling and sensor activation. By adding a mail server on that network I could enable the app notification, etc. but that would mean always being on that private LAN or a dedicated device which isn't a big deal since I have a number of smart phones.