I have the Leviton DW4SF. I just found out today that you can add it with a dimmable light switch button to your dashboard and it does change the fan speed.
You just add the Leviton app to your configuration.yaml:
# leviton config
light:
- platform: decora_wifi
username: "username"
password: "password"
Here’s an example of what I mean for the dashboard button:
type: light
entity: light.master_fan
name: Master Bedroom Ceiling Fan
icon: mdi:ceiling-fan
hold_action:
action: toggle