It wont happen because Microsoft want a licencing fee for using it so stock android doesn't use it.
If you format the SD card for use as internal storage then this uses Ext4, so the phone can definitely read and write them. But I don't know if it can read and write a card that is formatted with Ext4 for use as portable storage. I would be very interested to know if someone could test this!
I doubt it as Windows cannot natively read Ext4 because it is Linux file system, if you formatted an SD card with Ext4 then that would render is useless as portable storage.
Not for people who don't use Windows.
@madbilly So people should just switch to Linux?
Considering Windows is used on far more computers worldwide than Linux I would say that compatibility with Windows is far more important.
I didn't say people should switch to Linux. I agree it's strange and frustrating that exFAT support isn't provided. If it's possible to format a micro-SD card with Ext4 and use this as portable storage in an HMD Nokia phone then this becomes an option for Linux users, but doesn't solve the problem for Windows users (without adding new drivers into Windows anyway).
ExFAT isn't supported because it is proprietary Microsoft file system and requires a licence to use. For all intents and purposes the Nokia 8 is an Android One device and therefore what it does and does not support is down to Google not HMD.
Just a quick Google search and it appears OSX doesn't support Ext4 natively either so just how portable would a portable storage solution be if nothing could read it?