Nextion Touchscreens. It appears that Chinese sellers are very precious of their Nextion stock. So much so that, even when a customer pays for them, they won't send them!
Both sellers on Ebay and AliExpress have left me screenless and refundless too.
I've tried again, but this time with a UK-based seller. Much more expensive, but surely more reliable.
We shall wait and see!
Once the screen arrives I'll be test fitting it in my GBA case. Being 2.8" it should fit the hole nicely; it's more the depth of the board that may be the issue. I may have to cut out some of the cartridge slot assembly to make it fit.
Then it's a waiting game to see if my Nodemcu boards arrive. While waiting for those I'll be working on fitting the Pro Micro slave and breaking out it's pins, ready for the Nodemcu to drop in when it arrives :-)