I have a bunch of cameras from various vendors, some with open FW, some with their original FW, all cut off from the internet. They used to be connected to Frigate but due to performance issues I offloaded the work to Scrypted on a RPi and an AppleTV and the setup works great. It was easy to set up and it's easier to use than any other app, assuming you are into the Apple Home ecosystem.

It's not really self hosted since it relies on Apple but it's the least evil at this point. Giving unencrypted video and audio to some company (if what OP says is right) would be way beyond my risk tolerance point.