Don't Buy New – Upgrade Something Old (a Honeywell standing fan to be exact)
mulliken.netSo I have a mixed feelings about this.
From one side, it is great when people experiment with IoT -- this is became really easy and cheap in the recent years and more people should do this!
On the other side, there are basic safety problems. Judging by the photos, the uninsulated ESP32 board is next to the main control board, which pretty likely contains live voltage... and all of this in a moving and shaking device... This just sounds like a recipe for a large bang few weeks later.
There are also smaller problems with execution -- like the whole "cutting and measuring the voltage" to find out the where the power input is.. this is what the multimeter in continuity mode is for!
(also if I were to make this from scratch, I'd recommend to use pre-existing "esp8266 relay board" -- they are neater, more reliable than manual wiring and come in either DC or AC input variety... but I do understand the desire to use existing parts!)
I have added a note to the post. Also I am going back and making sure that everything is electrically isolated.
Thank you for the feedback!