But for what? The exported data file? The xattr data (resource fork in Mac of old) is stored separately from the actual file itself.
Tinderbox does export $Tags to DEVONThink.
As it happens, I’m currently helping another MarginNote user (privately) with this issue and it’s quite plain the problem here is lack of functionality in MarginNote. As it’s not a cheap app, why not get the MarginNote dev to give you decent import export rather than try an make other apps deal with MarginNote’s lack of functionality?