I was going to refer you to the same conversation JD linked, but it looks like you’ve already asked some questions there so I guess you want some more specific recommendations.
I’m using both the first and second options in my house so those are the ones I can speak to comfortably.
Option 1, the Home Depot Zigbee fan controller, is the cheapest, and the easiest to retrofit: Take the fan down or open up the canopy, depending on the model, and wire the receiver between the line and the fan. This gives you control of the light (including dim) and the fan (4 speeds). Note that if your fan uses capacitative speed control this may yield unpredictable results.
Control options:
A. Leave the switch in place for convenience of resetting, put a switch guard over it so nobody kills power to the fan, and stick the remote on the wall with a remote holder like this:
Or talk to this guy and combine the switch guard and remote holder:
B. Buy the extra controller for the wall remote as detailed in the link above.
C. Install a button or scene controller over or in place of the switch. I use the Lightify button with press for the lights and hold for the fan.
Since you’re coming from Iris maybe you already have zigbee smart plugs you can use as repeaters; make sure to put one as close as possible to each fan. With those in place, I haven’t had any issues staying connected to the hub (hub on 1st floor of townhouse, fans on 2nd and 3rd). Note that the DH for this controller requires the Classic app.
Option 2, the GE light and fan switches, are straightforward if you already have separate wall switches; if you only have a single load wire going to the ceiling fixture, you would need to run new wiring in the wall and replace your single gang box with a double gang box. I chose this option when I had an electrician install new overhead fixtures in rooms that only had switched outlets; since he had to run the wiring anyway, this makes it simple to swap out the switches if I want to move and take them with me. This gives you separate and intuitive controls for light (including dim, if you choose) and fan (3 speeds). You also have the option of using a device handler that allows double-tap controls; I use that to control switched outlets in each room.
Note that neither of these gives you reverse capability…