The commercial version of this works well right up until the vendor changes their mind about what you pay monthly, or shuts the service down.
So: a Pi Zero 2 W, go2rtc to bridge the camera's RTSP to WebRTC so a browser can
show it with low latency, two-way audio, and MQTT so the rest of the house knows
someone is at the door. Everything is a systemd unit with a documented restart
path, because a doorbell that needs a person to fix it is not a doorbell.