One of the things I'd been putting off through pretty much cowardice, was updating my Zigbee coordinator. However, this morning I said fuck it and found the tabs that I opened about it again.
This turned out to be a great idea because not only did I have the tabs for the wrong device open, the right tabs updated and now the process was simpler than ever. Hooray!
But there was some extra stuff in there, no longer was it just about updating the dongle, now it was about enabling Matter/Thread and switching from NCP to RCP. Network Co Processor to Remote Co Processor to the ignorant like myself.
I didn't opt for this, but I'm wondering if I should? If any of you have?
BTW, the only issue I had with my set-up after upgrading the dongle firmware is that I had to manually restart the Zigbee2MQTT container afterwards and the initial cable I was using, wouldn't do the upgrade, so I switched to my cheaper one from AliExpress which did it with ease, but that was obviously beforehand.
Edit: Here's the resource I used: https://dialedin.com.au/blog/sonoff-zbdongle-e-rcp-firmware