Just got three Matter accessories and tried setting up using Google Home. It immediately asked for a Matter controller to be present on the LAN before pairing/discovering could start. After a while, it was concluded that Google Home app does not support LAN mode access (without Internet) on Matter accessories.
Without the LAN mode access, there is very little difference between the Matter accessories and the existing fragmented cloud mode based IoT accessories. It is a shame that Google Home app did not implement Matter support correctly.
An ideal Google Home app should have the following functionalities:
1. No requirement of Matter controller in order to discover, pair, or access Matter accessories.
2. Default to work in LAN mode to discover, pair, and access Matter accessories.
3. If LAN mode operations fail, it then tries cloud mode operations to look for a Matter controller to reach the target LAN and again uses the LAN mode to discover, pair, and access Matter accessories.
4. If both LAN mode and cloud mode operations fail, it retries and quits.
BTW, Apple Home fails as well. Alexa is the worst by just relaying Matter access to IoT manufacturer’s cloud mode app.
