ESPHap VS esp32-homekit

https://github.com/Mixiaoxiao/Arduino-HomeKit-ESP8266 you mentioned above, is a port of the espressif lib to nonos/arduino core. It shares the wolfssl lib used by espressif, but as it is portrd to nonos, wifi disconnects during srp and devices cannot connect to it. There’s an improved version here: https://github.com/Yurik72/ESPHap which have patched wolfssl that I have changed to prevent wifi disconnections on SRP calculations. Yuri (the Author) made a great job improving original port, like memory management, moving pairings storage to the file, and so on. It still has wolfssl, which is at least redundant as arduino core already have bearssl bundled. Also, this lib has a memory leak during the pairing process, which is not so important as pairing usually made just once. I am currently trying to find where this leak is, but looks like it is somewhere in between the lib and wolfssl. So, I’d like to replace wolfssl with bundled bearssl, if I’d have a free tome to do that.

I would probably base the design off of a ESP32 microcontroller since it has WIFI and HomeKit libraries https://github.com/younghyunjo/esp32-homekit (just one I found, I have never used this library so can’t say whether this specific one is good). You can get ESP32 development boards to prototype with cheaply on Amazon etc, but I personally use Adafruit’s dev boards (like the Feather Huzzah32) even though they’re a bit more expensive. The quality is good and they have an absolute tonne of example code for basically everything. Really cannot recommend Adafruit enough as a starting point for all this stuff. There’s so much information in their learning guides. https://learn.adafruit.com/all-about-leds

Once that part was done, I'd look at the various home automation protocols, possibly even Homekit (https://www.espressif.com/en/news/ESP_HomeKit_SDK or https://github.com/younghyunjo/esp32-homekit).