...There are no AC batteries. It just isn't possible....
The term
AC Battery has been in the vernacular for a while now, not sure who coined it. Have to love marketing types! As it refers to a class of products sold as that classification, I hope most people will understand what I'm talking about.
At a minimum, it seems to be a battery, inverter, and
charger. An AC battery for
grid backup (e.g., Tesla, Enphase) must also include in the "system" an ATS to prevent back-feeding the grid. Both Tesla and Enphase have those and are also capable of controlling microinverters. Additionally, Tesla's system can also work with a variety of string inverters.
I believe (not sure) that Teslas controls the microinverters like most AC coupled solutions do (relay that disconnects them). The Enphase system talks to the microinverters via ethernet over powerline and tells them what to throttle at. I've heard Victron can make use of UL 1741 (frequency shifting) to throttle them, one of the members here reported they have just started testing will hopefully post their findings). If so, that means it should be able to throttle any UL 1741 compliant microinverter/string-inverter.
Not sure how you are saying there are only 2 solutions: Two solutions that fit the OP's situation? Two AC coupling solutions? Two with transfer switches?
If you know of other technical solutions beyond (1) AC battery systems designed to manage microinverters (i.e., Tesla, Enphase), or (2) AC Coupling (e.g., Skybox, Sol-Arc, Schneider) I'd love to hear about them!