> it seems like there should be a way to manage the devices on your network

Administering devices with network settings is convenient, but rapidly vanishing because there's no technical difference between you administering your local network and a totalitarian ISP administering their users.

My ways of dealing with the modern world, in order of preference:

1. Use Free software, so that devices develop user-empowering features instead of being locked down.

2. Firewall all general Internet access from a device/VM, and let it talk to local network devices only.

3. Firewall the device/VM from accessing most of your network, allow Internet access (ideally through a VPN), and inspect the hardware to make sure there aren't microphones or cameras.