My rules seems much simpler and lower effort:
1. buy the Zigbee version
2. boom, local only smart home is done
I guess if there's a device that's actually wi-fi only then I'll have to go through your flow but so far there's been no need.
Similar, with z-wave instead of zigbee. Except after installing two smart switches, a motion detector, and two smart outlets, I realized there aren't really any automations that I actually want. My porch light turns on and off at sunset and sunrise, through an electronic rube goldberg machine that could have just been a single photocell lightbulb.
Not contradicting or criticizing, just describing my lack of creativity.
Reasonable!
I found a few wifi and bluetooth devices that were cheaper than or didn’t have a zigbee equivalent. Window fan and air monitor specifically.
I didn’t do an exhaustive market search, just sharing my anecdotal experience. It’s a great feeling to be able to focus on hardware capabilities and price, then will the software you envision into existence via AI accelerated RE.