Regarding the NVR solution, I personally use both Frigate (Opensource, Free. Fantastic object detection, Really QUICK and accurate detections too), and Blue Iris (Closed source, requires 45$ license. But- amazingly powerful NVR software).

For cameras, I recommend POE cams. I Personally use reolink RLC-520s, and the likes. They support RTMP, RTSP, ONVIF, and will work with any NVR solution worth its salt. They are also quite cheap, and so far, have been pretty reliable. Of the 20 or so I have deployed, I have only had one die- which was due to it catching all of the rain coming off of the roof... in a storm. Warranty was honored on it.

Otherwise- as long as the camera supports one OF... RTSP, RTMP, ONVIF, you should be gold. For doorbell camera, Amcrest has a few options. I have an older AD110. They have newer offerings now. I do believe either reolink or amcrest also makes a POE powered doorbell camera, which would be good, if you have the ability to run POE to your doorbell.