I just now installed the latest Pico 75W firmware v1.03 and found that it does have preheat. You get to it the same was as on the Pico 25...by turning the mod off, then pressing the fire and + button for a good 3-5 seconds. But I believe this is only for temp control, just like on the Pico 25.

Therefore, I just reinstalled AF.

The Pico 21700 has preheat that can be used for wattage mode but I still use AF cuz I like it better.