I can confirm that you can have Two sprinkler controllers on the same app/same account. So if you need more than 8 zones you can just add another controller . Mine has 6 zones (Front yard ) and 7 zones ( back yard).
How did you wire the 2nd controller? I’ve got 9 zones in a Hunter system that I’m replacing. If I add a 2nd Wyze to handle zone 9 how is the common pulled if it is in the Wyze #1 controller? I’m willing to leave zone #9 in the Hunter System and add my new Wyze for zones 1-8. Just not sure if and how it would be done.
I had two sets of wires for the front and back controllers. Both are separate and in no way connected.