Initial proof of concept, with vast land for improvement code-wise (planned to use StaticJsonDocument everywhere and I need a better layout/split between files). After a lot of struggles in the past week and weekend, I abandoned the idea of using my fake WeMos D1 minis v3.0.0 as I was never able to flash them. I guess I will be sticking to the NodeMCUs v0.9 and standardize on them, or switch to the (fake?) WeMos v1.O.0. Unfortunately, genuine boards are double the price of fake ones or NodeMCUs shipping included.