If the Skybell doesn't work out, you might just consider a Wyze cam mounted up top. I bought the outdoor mount for $11. Routed black CAT 5e inside and down to my basement to plug it in, since I don't have an outlet near my front door. I cut a micro USB cable in half and coupled the appropriate USB ends to the Ethernet cable.
The particular path the cable takes for me, allowed me to splice into the same cable and use two of the remaining 6 wires with a regular doorbell button. On the other end where the Wyze power adapter is plugged in, I attached two wires I soldered to the reed terminals of a Xiaomi contact sensor (choose your favorite sensor for this task).
When someone presses the doorbell, HE triggers IFTTT > Wyze, and that takes a 12 second video clip (No service fee), The closing of the contact sensor triggers Alexa to announce "Someone is at the door. I haven't installed it yet, but I also modified a Xiaomi motion sensor for a 5 second hardware timeout. So when someone walks up to the door, instead of using the Wyze motion detection (which is overly sensitive like most camera based motion detection and is limited to 30 seconds timeout before the next clip), the Xiaomi motion sensor triggers a rule that uses that IFTTT automation to take a clip from Wyze as often as I want in 5 second or longer intervals. The frequency is adjustable by altering the motion sensor "reset to inactive" time.
I also use HE and IFTTT to send me notifications when someone walks up to my door and when they push the doorbell. Currently with the Wyze cam motion detection, there's about an 11 second delay for IFTTT notificaitions. The doorbell takes 3 seconds for Alexa to announce "Someone is at the door" after the button is pressed, and the IFTTT notification comes 1 second later. So I should then get my first recording within 5 seconds or so of the motion sensor detecting and that will be roughly the same timing for showing me the Wyze cam on the Google Home Hub, and whatever else I want to do, like turning the porch light on (which I do already with the Wyze motion detection).
Soon I'll also have a Google Home Hub. Wyze is releasing an update the end of this month that allows you to see your Wyze cam. In the demo it was pretty fast. So with the Google Assistant Relay, I can have motion trigger the Google Home Hub to automatically show me the Wyze cam, and I can even use those capabilities allow me to ask Alexa to show me the front door and HE would then trigger the Google Home Hub to show me that Wyze cam by way of Google Assistant Relay.
Wyze also just released a beta that supports viewing multiple cameras as once. I'm guessing if they can, they'll add that capability to the Google Home Hub at some point. They also have RTSP support coming.
