This is something for the developers. From what I have tried it leads me to believe that all "Folders" must be only in the $Home. Their has to be some way if you want all of your documents to be located on another drive you should be able to assign Documents to a drive of your choice. I did notice when I
I have also posted how to set TB up to use the same drive for Windows10 and Zorin 16 on Mozilla forum.
For clarity, you can note over there that Zorin OS 16 is built off of Ubuntu 20.04. Just in case they are confused about what build they are working with.
Received reply back from Mozilla with a comment of "I hope you've done your homework on what could go wrong with that setup". After reading the many how to do it I have decided I need to change the way I have been doing things for the last 25 years. First I am going to look at things a little different like My Documents & My Downloads drives in "+ other locations" as a server where I would store things not used often but should keep. Use the document and download directory as intended. Things in those directory's that are over 1 year either purge to trash or move to permanent storage (My Doc. & My Downloads.)
This is a common thing where I get absorbed in trying to solve a stated problem, it does not occur to me to question if there is a problem to be solved.
I use the directories as intended and use the Cloud or External Drives as intended.