I've had this Vornado 660 for years and didn't want to swap out a working fan just to control it from my phone. So I wired transistors across each of the physical buttons and let an ESP32 tap them. The fan's own controller still handles everything on the mains side; my board shorts the button signal lines to ground, which the fan reads as a fingertip press. Parts ran about $13 and it took ~4 hours on a Saturday.
The mod is fully reversible and reflashes over the air after the first flash, so the fan never has to be opened again. Wiring schematics, the ESPHome config, and build photos are in the repo. Happy to answer questions.