If you want to use a quorum device - in contrast to a quorum server - then you'll need a LUN to configure your quorum device on.
It does not matter whether this LUN will be used later as a zpool or as an SVM metaset.
There is one exception, that should be mentioned in the docs. If the LUN used for the quorum device is later used as a disk for a zpool, and this disk gets a new EFI label, then, I think, the quorum information can get overwritten. So be careful in this specific situation and consult the docs before doing so.