"Sensors -> zigbee or zwave -> home assistant"

Home assistant gets updated quite frequently and so does the OS that runs beneath it. My point is that the chain you are describing here can be (is) one single device, with no outside dependencies that runs the logic on a room level. Quieter computing is if it works without the constant upkeep.

Indeed I think there is a lot of work remaining to be done to make a 'it just updates itself and everything is fine' workflow for home assistant as a container on top of a linux-based platform that a completely non technical user never has to worry about.

Basically something that requires no more level of technical sophistication (zero) than an xbox series x updating its operating system, which requires nothing more than a user to click "okay" and wait for it to reboot, if you power on an xbox and bring it onto the network and its software is several months out of date.