I heard some people confine cameras to a seperate virtual network which can't talk to the internet.

I don't have any specific camera or manufacturer to recommend. But Frigate is a nice peace of software. Maybe their community or the Home Assistant users have some advise.

If you like coding and soldering, you can buy an ESP32-S3 camera and do the entire firmware yourself. I don't think they're as good as off-the-shelf cameras, though. And I think most of them come with a cheaper OV2620 camera, which is more close to potato camera quality. So if you go that route, spend a few $$ extra to get one of the better camera sensors.