I’m sure this guy’s dad that needs help installing Linux will appreciate the clarification, good thing you’re here to point that out

You’re not wrong about reolinks, amcrest, hikvision, etc but their price:quality can’t be beat and they work well with many different NVR software suites, which makes them popular.

If you’re concerned about how they call home (they do, I’ve sniffed packets on my network to test the rumors and seen it on every one of them), you need to isolate the cameras off of the internet so they are blocked from the outside connection. This can end up being mildly tricky to very complicated depending on your network equipment, the way your LAN is set up at home, whether you want to view your cameras remotely, etc, but it’s the most cost effective long term option that is not subscription/cloud based.

I use blue iris on an old computer. It works great. I have unifi network gear, and I tried some of their cameras out but they’re not really ONVIF compliant and they’re extremely expensive for an equivalent Chinese brand. That’s the made in USA price, and tbh Unifi cameras aren’t even that expensive, they’re more “prosumer” for small business deployments or nerds at home. They have a walled garden ecosystem that I dipped my toe into and didn’t care for some of it, but I still use their access points, routers, and switches because they’re great quality and really easy to config.

But, if you have never done any of that, you might just want to go with an off the shelf solution or be willing to spend a lot of time reading. You DON’T want to mess up your network security trying to install local cameras if you’re not sure what you’re doing.

One thing that hasn’t been mentioned yet is an RF/analogue camera kit. It’s not as easy to set up as POE (two cords to each camera and they’re way bigger so running them through walls will do more damage that you have to patch later) you can get an all-in-one NVR+4/8/12/16 etc camera kit with as many bells and whistles as you want. It will be cheaper as well and you don’t have to worry about network bandwidth issues because it’s analog. The feeds are super nice.

Even if I replace the speaker from a telephone, and the keypad stops working a month later, I have voided the warranty already by doing the speaker change as they can’t know if the now not working keypad was done because of you or a failing unit.

This is false. They have to PROVE that the repair that you made caused the keypad to fail in other to void your warranty, at least in the USA. Most people are misinformed as you are however, and they’ll TELL you that’s the case to make you go away, despite it being illegal.

https://en.wikipedia.org/wiki/Magnuson-Moss_Warranty_Act