If you have an old bell built into the door you can hook the old button up to anything like an esp32, and if you don’t and therefore need to put a wireless button on the door (like a battery operated ring) you can do the same with an esp32 plus a battery.
You could probably even buy any random old wireless doorbell and make it ‘smart’ by reading the output of the speaker unit.
On top of that, putting a camera through the peephole if available is also much easier than one would guess.
If you have an old bell built into the door you can hook the old button up to anything like an esp32, and if you don’t and therefore need to put a wireless button on the door (like a battery operated ring) you can do the same with an esp32 plus a battery.
You could probably even buy any random old wireless doorbell and make it ‘smart’ by reading the output of the speaker unit.
On top of that, putting a camera through the peephole if available is also much easier than one would guess.