SIS is done at WAFL layer and thus the limitation is at that layer. I dont think MS DFS will circumvent the limitations as WALF does not care what other layers are on top, however I cannot document this, its just how I understand SIS.
Let me know if you find otherwise.
Hope this helps.
Re: Using symlink as a workaround for ASIS limitation on volume's size ?
Also, depending on the nature of the data in the volume (i.e. how much it deduplicates), it's possible that you might be able to progressively migrate the data over with dedupe in between (migrate some, dedupe, migrate more, dedupe again, etc.).
And...while it would cost money, you can upgrade a 2020 to a 2040 with a rear head swap (3x the dedup limits I believe).