I have a ducted 14kW single phase Panasonic unit connected to a MyAir 5. I had it installed with MyAir straight away along with the individual temperature sensors.
You’ll have to ask your local MyAir installers if they’d be happy to retrofit to your existing system, I’m sure they would though. In terms of sheer compatibility, probably easiest to contact Advantage Air support. I’ve called them on the phone once about some functionality (enabling economy mode, fyi not possible via myair) and they were quite helpful.
We’re still not there on great integration with Home Assistant yet. Aside from the pymyair python library and cli tool (which I hope still works) this commit is the sum total of my work to date on the home assistant integration: https://github.com/smallsam/home-assistant/commit/e346b6e4e339c350a4d3d6c26e65f09dc3ef7977
that I spent time on last year. Too little time to code these days and little motivation as it’s Winter…