I want my house lock to work like my car fob. Unlock when my hand touches the door handle if it senses the fob close by. And the fob should double as a batter

I want my house lock to work like my car fob. Unlock when my hand touches the door handle if it senses the fob close by. And the fob should double as a batteryless RFID in case the battery dies. Oh, and can it be a bit slimmer than my car's fob please?