ThetradingDILFB

If it’s broken and you want to automate it get the door knob not the handle. The door knob ones have a backup key

The adapter you have seems to do the trick, I think most of us would lean towards a traditional doorbell transformer hooked up to the nearest power supply junction box. Which then you only have two wires from your transformer to your doorbell. Polarity won’t matter on the doorbell. I think that would be the cleanest way to do it. Also consider looking at your local codes and the doorbell manufacturers requirements.

Motion detector at best.

I’m think biggest thing you can do is don’t introduce cameras inside the home. Use motion sensors instead. Your digital footprint is out there regardless , if you use any type of technology.