I don't know if this has been discussed before, but I'll share it anyway:
The GR III has 35/50mm crop modes that, even if you shoot raw, won't display the 28mm FOV when you try to "crop out" in apps like Lightroom. The data is there in the dng file somewhere but somehow is not accessible. I searched online and found two claims on how to get the 28mm FOV out of a cropped 35/50 GRIII dng raw image: one was affinity photo (didn't work for me) and the other was DNG Cleaner (available trough App Store / Microsoft Store). The latter worked for me and I even got more resolution than ricoh probably intended (6020 x 4024).
I don't know why that can't be accessed trough Lightroom but anyway, spent the 10$ on the app just in case I ever run into a situation where I'd want to "crop out" after shooting in crop mode in camera. Probably would work for the IIIx with the Teleconverter attached without having to resort to taping over the electrical contacts.