Has anyone had an issue with PowerWalls and mini-splits?
I have a Mr. Cool 18,000btu mini-split on my garage/shop, the the PWs have no trouble running it, and the 4.5 and 3 ton main AC units simultaneously here in the worst of az heat, but I have 4PWs. The mini-split I have only runs at about 2400-2700 watts during normal cooling operations, and seems to have a slow ramp-up feature - so I've never really seen it spike above 2800 watts or so. Not sure if that's true of all mini-splits. But 2800watts will be fine for even one Powerwall if the rest of your peak load isn't much above 3000 watts continuous, or 4000 watts peak.
You have measure your normal house baseline load, and add test/measure the other large loads that are specific to your house... something that's a bit unique to each home that you pretty much have to measure for yourself before purchasing. I spent $99 on a whole home mains load measuring device that works with my Smarthings hub, that gives me live readings so I could turn on various devices, ultimately turning on all my main "large" load devices at the same time to insure I knew my peak loads before investing in solar and PWs.