Out of the box thinking! Something like this never entered my mind . Thank you!
I would set it up so it would only work in Away or Night mode (and use the key fob to set Away mode), as hubby is retired and he said he doesn't want to have to unlock the door every time he goes outside for some reason. Our use case may be different than for those folks that are away from the house often.
I can only think of one gotcha, and that is forgetting to shut a door at night. When the weather is nice, we leave the back and garage doors open all day. It is hubby's duty to check the doors at night and sometimes he forgets. Right now he has an Alexa routine "Goodnight" that turns on a hubitat virtual switch that locks all the doors. If he forgets to shut a door at that time, he needs to be admonished! I see TTS coming in handy there...need to think about this more.