Ditto Girish Shah and TimoG - for me the whole thing is unusable in a key business process unless the storage is sorted out so I am surprised by surface-level changes until this is completed. The storage should mirror Teams meeting recordings and Lists - channel whiteboards stored in SP site of the Team; individual whiteboards stored in OD with the ability to selectively share; whiteboards created in meetings mirroring the meeting (e.g. channel meetings vs individual invites outside a team going to SP and OD respectively)
Doing half a job here will keep users in Mural when they feel the pain of losing all their work should someone leave, stop sharing, move role and delete their version of the whiteboard file without realising the rest of the business is using it etc. etc.