As far as I know the hardware on the MI 6X (which runs MIUI) is identical, however if I understand correctly the way the storage is formatted is different.
I have read that it is possible to change, but not sure if it will work with this firmware.
Some use stock 6x firmware while others use xiaomi.eu rom of 6x
But I see people bricking their devices all the time, Mi flash stuck flashing or failing to flash resulting in a bootloop and a fastboot that no longer works
OR triggering arb by either updating or flashing without deleting the files responsible for changing the arb value so they can no longer go back to A2, and edl will no longer work because it's a 6x now
So my question is, would it be possible for you to take your 6x rom, remove arb and make work with A2 elf files, so if you decide to use an A2 rom, you wouldn't have to go through this dangerous process
It would be awesome if you could do this but I'm just asking if it's possible