How's the board working out for you? Is the control circuit for PWM control of the fan working well?From there, what you do is up to your imagination. That being said, I'm more and more leaning towards coding a project outside of esphome. If it was just for me, I'd go for a native esp-idf project since I'm very familiar with the environment, but I might also go with the Arduino framework. It does add a massive amount of bloat and can be frustrating to work with, but it's more accessible to a broader audience I think.
Nonetheless, you are right; the UI could be built with lvgl and speed control could be supported as a slider. Something to think about.
Oh and the button there is a rotary encoder with push button, so a good clicking feeling and no limits on number of turns
Does the fan go to 100% while the ESP is being programmed/rebooting? IE same as the fan being powered but unplugged from AC Infinity controller?
Can you share the schematic (or easyeda project)?
I was thinking of making a test circuit to try out a basic opto design. Wondering if R1 would prevent the fan from it's fail-safe ramp to 100% with a weak pull down.