I may be missing the obvious here but unfortunately the Airtable support pages do NOT explain this. I'm on Enterprise.
It looks to me like there is no way to restrict read/write access to bases within a Workspace. I can only see "creator" and "editor" and "viewer" setting on a WORKSPACE level. All bases within that workspace seem to simply inherit those settings.
At the same time, I also cannot see the possibility to sync between bases in different WORKSPACES. Or at least when I created a new workspace and a base within that, I was not able to sync/link to a base in the other workspace.
What we're trying to do is simple... have interconnected/sync'd bases but each base has different write permissions for specific users. Is that really not possible?