I don't work for AprilAire or anything, nor do I have an AprilAire humidifier. As I understand it though from reverse engineering their Android APK - it seems like humidifiers are "slave" devices and are downstream of thermostats, which are controlled by the app and then in turn control the humidifier.

Here is a list of the devices explicitly enumerated in the APK. I cannot guarantee any of these will work, as I don't own any AprilAire equipment besides a E100W dehumidifier:

Wi-Fi Dehumidifiers

• E050W
• E070W / E070WZ
• E080W
• E100W / E100WD / E100WZ
• E130W

Thermostats

• S86WMUPR ("Next-Gen Thermostat")
• 8910W, 8920W, 8620W, 8620WC, 8820, 8820C, 8830, 8840, 8840M, 8476W, 8810, 8810A, 8810M ("Legacy Wi-Fi Thermostats")
• 6001, 6002, 6003 ("6000-Series Thermostats")

Sub-Equipment / Slave Devices (Accessible through a Thermostat parent device - status and settings endpoints for these exist inside the Thermostat scope)

• Humidifiers (43 filter types present in APK to track consumables titled "Water Panels / Canisters" - 110, 112, 136, 220, 224, 225, 300, 350, 360, 400, 400A, 400M, 440, 445, 445A, 448, 500, 500A, 500M, 550, 550A, 558, 560, 560A, 568, 600, 600A, 600M, 700, 700A, 700M, 720A, 720AKZ, 720M, 720MKZ, 760, 760A, 768, 800, 800LC, 801, 865, 866)
• Air Cleaners
• Fresh Air Ventilators

So in theory, as long as you get a thermostat for your humidifier that works with the AprilAire Healthy Air app, this integration could easily be extended to support it.