Today, I took a closer look at some sites introducing DIY Zigbee devices and noticed something right away: the author is using the same Zigbee module as I am (E18-MS1-PCB from Ebyte).
In the past, I tried to look for projects or information about this CC2530-based module, but didn't find much. However, I thought it was worth another try since someone is actively building Zigbee devices with it.

As usual, I used my best friend Google. Using the keyword "E18-MS1-PCB", I went right away to "Images" and after scrolling for a but, this caught my attention:

I mean... the image title speaks for itself, right? With high hopes, I clicked on the image and was directed to Z1 Mini Development Board lets you build custom ZigBee end devices. Unfortunately, after reading the article, I didn't find anything new on the horizon. To be sure, I checked the linked Wiki page, and there I found this:

Great firmwares? For the CC2530 chip... For a moment, I thought these might be the firmwares for the DIY Zigbee devices I mentioned earlier. Or maybe ready-to-flash firmwares to use a CC2530 as a ZNP device?

Well, it turned out to be even BETTER than that: A GUI tool for creating your own alternative Zigbee device with a flexible configuration of inputs and outputs.

This is incredibly promising and might be the solution I’ve been looking for to easily make a Zigbee device to enable connectivity for my air conditioner with Home Automation. I’ll be spending this Golden Week holiday diving into this!”