Face buttons swapped
I went ahead and swapped the face buttons - they do indeed fit in either slot (A/B and X/Y), and they're not too hard to access once the device is open.
Opening the shell was the hardest part. I couldn't avoid some light scuffing of the shell around the power/volume buttons, and it took a fair bit of force with the pick to get it open.
Once inside everything was very straightforward: the battery and speaker were easy to disconnect, and I didn't have to remove any ribbon cables to access the buttons - nothing fiddly at all, thankfully. The PH00 screws holding the right PCB to the front shell were a different length to the rest of the PH00 screws, but other than that they were all uniform.
Closing up presented one minor niggle in that the four T3 screws that hold the shell together were magnetised and thus repelled my screwdriver, so I had to use angled tweezers to get the screws back in their slots and be careful not to drop the top ones inside the casing in the process.
Otherwise no real surprises - everything was as in the Mangmi teardown video except for a strip of tape over the protective cover around the fan. The whole task took me around half an hour, with a fair bit of that attributable to an abundance of caution.
If anyone wants to repeat the feat, I definitely recommend following the relevant parts of the teardown video (including remembering to remove the MicroSD card before opening the shell, and to disconnect the battery once inside). I used an iFixit Essentials kit for the pick and tweezers, and a Fanttik E1 Max electric screwdriver for the screws. I also used a silicone work pad and the foam insert that came with the Air X's packaging to rest the device on and prevent the face buttons' silicone pad popping out when I put the device down.
