For openers that are directly WiFi enabled, the MyQ controller is integrated right into the head unit. Mine is a WD1000WF. The WD denotes Whisper Drive and the WF denotes WiFi built in. It’s the WF indicator that signals having WiFi built directly in (and therefore being directly MyQ enabled).
For openers that do NOT have the WiFi directly enabled, the add-on MyQ device has both a network connection (wired ethernet) and a remote transmitter function (just like the ones included with the opener). This is why you “add” the MyQ device as a remote to the opener. Once triggered by a network function, it transmits the operating signal to either open or close the door. Additionally, it has circuitry and logic in it know whether the door is open or closed.
For those openers that are WiFi enabled with MyQ directly integrated, the add-on MyQ device is still an option. In the event that WiFi coverage in the garage is poor, for example, a wired connection for the “stick” could still be viable.
Z-Wave GDO devices (I have one and it was super unreliable) don’t work with the new openers because the wired wall switches now have much more logic in them and do not operate purley on a momentary contact basis to control the motor. The wall plates monitor temperatures, offer “lock” settings to disable remotes, can trigger the light to stay on, have motion sensors in them to turn the lights on when motion is detected, etc. And this all rides over the same two wire connection that has been there since the beginning.