I am in a different situation. Since I’m quadriparetic, I don’t have the usual “Plan B“ option of just walking over and turning on the switch since neither of those actions are physically possible for me. So local control is quite high on my priority list. As I’ve mentioned before, I even have one set of switches in a pathway from my bedroom to the front door that have local voice control through echo. But these emergency switches are linked to an Echo device, not ST or HomeKit, because that’s the only way that local voice control works.
https://www.amazon.com/gp/help/customer/display.html?nodeId=GCC6XV9DX58VW5YW
These are strictly my Plan B devices, typically in the auxiliary position for a two-way set up in the room. They will work manually for the other people in the home if necessary, and they will work through voice for me as long as the local Wi-Fi network is still operational. No Internet required once they’ve been setup.
I am also able to use voiceover on my iPad (the voiceover accessibility feature, not Siri) without an active Internet connection, so I can use apple’s HomeKit app that way, again, as long as the local Wi-Fi is active, but this kind of voice navigation is a lot more work than using a voice assistant like Siri or Alexa, so this option is more of a Plan C.
Use Voice Control to interact with iPhone - Apple Support
So different households will have different priorities, you just need to figure out what your own are and then plan for those.
We do have a how to article in the forum on planning for outages. that’s been there for a few years, but it never gets a lot of traffic, I think because most people just figure it out on their own once they realize they have to. even if it’s just, as you say, making sure that you can manually turn anything on or off that you might want to if the Internet was out.
Anyway, here’s that topic if anybody’s interested. It hasn’t been updated for edge drivers yet, but I think until edge comes out of beta we can’t really know how everything’s going to work. 