Trees

I use BlueIris (one time cost for software) and a mix of cameras that link up using RTSP protocol. If you search for BlueIris compatible cameras you can see big lists of cameras, but at the end of the day most anything that's RTSP is g2g (it can be a bit more complicated but generally if something is listed as RTSP compliant you will be able to get audio/video, and usually pan/tilt/zoom if the camera has it). I actually think that if you just want to use one camera you could just access it via VLC and its IP address, but I've never done it personally.

There's a YouTube channel called The Hook Up, guy does INCREDIBLE camera reviews.

Personally I use a smorgasbord of cameras, mostly from amcrest, TP-link, hikvision. Probably others that I can't think of. Another commenter recommended ubiquiti/unifi cameras. I do NOT recommend them, but they are very easy to get going. Problem is they're SUPER expensive and their quality is meh. In order to use them you either need to self-host the controller software or buy another expensive piece of hardware to go with the overpriced cameras themselves. On top of all that they are NOT RTSP compliant so you can't really use them outside of their ecosystem, which is BS imo.

I don't trust Chinese-made low cost cameras to not call home so none of them have access to the open internet, and I can view my cameras remotely using a VPN. Everything is fully locally hosted, no cloud shit.

Also, you can buy NVR+camera kits that don't call home. Analog ones with 4 cameras are probably pretty cheap these days and the video quality will be good. You'll have to do some digging to find out if a model is fully locally controlled but I know they do exist (and you can probably get a full NVR with cameras for less than the price of a single unifi bullet camera and a cloud key).