DIY Smart Home Doorbell 2.0 (works with Alexa) – Hackster.io

https://www.hackster.io/naran-inc/diy-smart-home-doorbell-2-0-works-with-alexa-690c33?ref=channel&ref_id=425_published___&offset=1

This looks worth to check out project:

Build your own DIY smart home doorbell for cheap, get notified when your guest knock at your door and remotely open by voice command.