Not a lot of choices here. And upthread are some stories about these devices damaging compressors or just not working right. In addition, power outages lasting long enough to make a difference don't seem to happen often here. Lastly, when you try to find somebody to do any kind of work, if you are lucky enough to find somebody, it's liable to be months before they show up. I had a really hard time just finding a handyman for some repairs and renovations, and would probably still be looking if my realtor had not recommended a friend of hers, who agreed to do some work for me out of friendship with her.
I don't even know how to tell if I have a scroll or reciprocating compressor. And even with a SureStart, are two PWs even enough? I have no way to determine that.
Again, it only comes up a few times a year for very short periods and isn't life-threatening. I know people here who choose not to have or use A/C because they prefer the natural air. It would be nice to have A/C when there's an outage, but I guess it's not important enough to justify the aggravation of figuring stuff out and trying to find someone who can and will do the work.
I don't think a lot of people here have Powerwalls. Until recently solar installations here were all net-metered so it wasn't an issue and installers have no experience. I'll bet that if I found someone to work on mine, I'd be their first.
Too much verbiage just to say it's just not worth the bother here. Sorry.