Based on my searches, I could only find 3* controllers that have this feature (and interestingly, they all do it differently). There’s the new 8BitDo Pro 3, where the face buttons are magnetic, the GameSir Supernova, where you have to remove the faceplate to swap the buttons, and the GameSir Tarantula Pro/T3 Pro, where there’s a motor that swaps the ABXY layout.
This seems like a pretty simple feature that would be really useful for multiplatform controllers. Lots of controllers advertise that they work with PC, Xbox, Switch, Android, etc., but very few of them give you the option to physically swap the ABXY layout. They usually have one layout or the other. I would get not having these features on a really budget controller, but there are some controllers that are really expensive and don’t have this neat little button swap thing (instead opting for gimmicky things like a screen)
edit: * There’s actually 4**, I forgot about the Nyxi Flexi!
edit 2: ** Nope, it’s five***, the Gulikit KK3 Max has replaceable button caps! Very cool!
edit 3: *** Actually, the older KK2 Pro also seems to have this feature too, as well as a few other older Gulikit controllers, so I guess it’s >6? That’s cool. With four different companies (GuliKit, 8BitDo, GameSir, and Nyxi) offering at least one controller with this feature, I guess it’s not as rare as I thought. Who knew?
Cost and not giving a fuck.