I mounted a $25 wyze cam outside my front door and then mounted a fire tablet on the wall inside my front door. Sideloaded the wyzecam app and set the device to always stay on when plugged in. Quick and cheap motion sensing camera that can be accessed from any of your devices as well. Throw a microSD card into it and get a few days of playback storage as well. You can ask alexa to show your camera on your fire tv if you have one of those as well. Mount those $30 fire tablets anywhere in the house to have a live feed.
Wyze came has motion detection, sound detection and person detection. Automatically records 12 second video on detection and uploads to cloud for free. No subscription required. The SD card records constantly so you can go back and playback. With full HD a 32GB card stores about 3 days worth of video with sound.
It also has a speaker built in so you can shout at solicitors through it if you want, but the speaker is pretty crappy so I wouldn't count on them being able to understand you.
In wyze cam app settings enable hardware decoding to prevent delayed video