danepak: In regards to power for the doorbell, I don’t understand why he ran two cat6 cables.
One is obviously for the future proof of a PoE camera.
Don’t understand the other one and I thought he would be running a small low volt power cable to power the camera doorbell.
Or maybe this will be added later?

The cat 6 is a small low voltage cable. That's fine to use with the nest! cat 6 is cheap, I would have done the same, gives me more options later on as there will be 3 spare pairs in the cat6 that supplies the nest.