Doorbell HA Augmentation Hardware

[dense junco]

We currently have a dumb (I think 24vac) old doorbell.
I want to add it as an input to home assistant and then have a chime in a different part of the house (while leaving the current system functional).

1. What sensor hardware should I use, I'm thinking a POE powered esp-board with some sort of isolated current sensor? (is the a ready made solution).

2. What chime hardware should I use, I'm thinking a esp relay board with a buzzer/bell... is there a ready made alternative (maybe a speaker)?

3. Is there a way to get a low latency notification on my android smartphone?

[cursive dune]

Put an energy monitor or smart relay across/in line with (as appropriate) the doorbell switch circuit

There’s a Zigbee or WiFi “siren” you can buy which works great - ignore the word siren, on low or medium volume it works great as a doorbell and there’s a doorbell chime sound built in

You can notify from HA, it’s not super low latency but it’s more than fast enough for a doorbell. I use it to alert me when someone is detected on my driveway camera and even after a round trip to an LLM to analyse a snapshot, it still notifies my phone before they get to the actual doorbell to press it

[grizzled spade]

The way I made my dumb doorbell smarter was to add a vibration sensor to the ringer part, no need to rewire anything, it's pretty much plug and play.