It's crazy, given that all these devices have something powerful like an esp32, isn't it?
I've done some of my home stuff this way, but I had to program it myself. Tasmota has some features which can be used without a server, but that's just for simple stuff like switches. For whatever reason (simplicity for non tech people?), out of the box products don't work this way.
If you don't have days of spare time, you buy ready made products and set them up in minutes in Home Assistant