Ask HN: What one app can I use to manage all the IoT devices in my home?

I write python scripts to control my devices, and made a web page to trigger these scripts: https://github.com/printfinn/smart-garage-rails. I run this website on a Raspberry Pi in my home, it's been working fine for half a year. It's written with Ruby on Rails, and one good thing it provides is that you don't need to worry about privacy, because it doesn't need to be connected to the Internet, only inside you home net.

Sounds like Home Assistant may fit your usecase well if you are willing to do some small initial configuration. https://www.home-assistant.io/

I am using node-red to control some lamps e.g. when it is getting dark and my phone is around (check bluetooth connection) then turn on the living room lamp.

You can do so many automations by using nodejs in the nodes.You can check it out here https://nodered.org/