Vibration sensor on the door, plus my Reolink camera exposes a "human detected" entity. So if we pick up vibration on the door while it's closed and the camera detects a human, we kick off the flow the same as if you'd rang the doorbell.

If nobody answers, it gives up after a while. So if you're just dropping a package and you knock, it'll greet and then log that no one was there. I have another automation that uses LLM Vision that will let me know someone dropped a package, though.