When the designers are working from home, they do access the files from google drive. But the problem is that they can't save the files to google drive.
Sorry, I don't understand why? If they can open files from the google drive, why can't they save them?
It would just be nice to be able to save them to either truenas or google drive and we get bidirectional sync.
Again, this is not going to happen, for the reasons I explained.
I still don't understand your workflow, but let me explain the workflow of a customer of mine.
CAD company that uses Dropbox. CAD software saves files under \\Server\share. Because the also saves the path it saved a file to, we can't use Dropbox. Everybody has the use the same path. But with Dropbox, everyone has a different path C:\Users\variableUsername
At the same time, some employees work outside with iPads and have to access all files.
I hope you understand why we were looking for the same solution as you were. Here is how we solved it:
A Windows Server is running the Dropbox App. The folders inside Dropbox are shared over smb. Windows employees access the data fast via local network or VPN, while iPad employees use the Dropbox app. If a Windows user saves a file, there is a short delay until the file change gets recognized by the Windows Server Dropbox App and uploaded.
Again, you have not explained your workflow, so I don't understand your needs, but maybe a Ubuntu VM with a Dropbox share could help? Just be warned that Dropbox is dead slow, crushes your SSD with writes, wastes a lot of CPU cycles. My guess is that the same is true for GDrive.