When I did my in floor heating in the master bathroom I went through something similar regarding the zones.
My goal was to be able to control a zone for the shower and a zone for the floor tiles everywhere else independently of one another.
Two separate lines are run in these areas under the floor to one two zone thermostat, on a dedicated line to my breaker panel. From what I found out during my process is that a two zone thermostat controls both zones at the same time.
I could not find any thermostat control panel that controls two lines independently and figured if I ever do a whole home in floor heating system each room would need its own thermostat.
Plus side to a two zone thermostat in a room is if one of the cables is cut in a remodel the other zone still functions.