I have the Dahua VTO (I forget model number.... it's the one Looney reviewed for the villa intercom system). For camera purposes, it works 100% (wide angled fish eye lens that is not too bad for the optical distortion, great motion detection from the camera itself, and can intercom any number of VTH sister units inside the house, which I have 3. This system is not touted as a 'doorbell' system but rather an intercom system. However, it is easy to convert to a doorbell system if you have home automation. Also sure you can somehow do wiring magic to hook up a standard doorbell chimer (which I have not done).
1.) The VTO integrates into
Blue Iris with a breeze and acts as any camera would.
2.) It integrates nicely with Home Assistant via MQTT and the Home Assistant Dahua Camera Integration add-on. Which in turn means you can have Z-wave, WiFi, or Zigbee devices to act as a siren/speaker...or if you have whole house audio, for audio notifications.
3.) Additional VTH remote monitors through out the house which means do not have to rely on cloud or smartphone use.
4.) still can answer on the smartphone when away from house using VPN and the DMSS application (which is a hybrid of cloud notification and local VPN answer/talk/see).
5.) downside is it's not $40
6.) fish eye lens captures nearly 180 degrees left/right/up/down which is a requirement for any door camera. crystal clear images of someone 2 feet away and pretty darn nice images from 50' away.
7.) my model (I am thinking..2202F-P?) is not WiFi but POE direct cabled.
I was going to buy a cheaper single purpose video doorbell, like options mentioned above by OP. But then got to thinking of above and beyond just a video doorbell. The VTO/VTH villa intercom system was the answer I was looking for.