Need at least the camera, if not that plus a microphone and speakers, not the lock or bell.
Libre Software (Obviously) + End-to-End Encryption
Small and easy to hide, so the camera isn’t stolen, attacked or bypassed.
Reolink has a local encrypted video doorbell.
I use Eufy doorbells, locks, and cameras. I realize they are a Chinese company, but that is almost unavoidable until the US gets back to actually manufacturing tech.
The reason I like Eufy is the local storage and no required subscription fees.
I use eufy as well. The only issue they recently had was that thumbnails were stored in their cloud if you chose to enable them on notifications. If you just select the text option, none of the footage is stored online and everything is local.
Harder for China than the US to attack in the US.
Here’s a very similar question I asked here a few months ago: “Privacy respecting ring doorbell” https://lemm.ee/post/8165932
You don’t need a doorbell camera, get a regular camera instead.
You need an app which will receive events from a doorbell via a server to receive data to interface with the app. Both of those things need to be owned and operated by someone to be approved for use on the app store. That’s why a custom open source of doorbell as you envision it doesn’t exist and never will.
I agree mostly except the app. Don’t pretent Home Assistant doesn’t have an app.