How to set up a unified database for all spaces

Very excited about the Datahub feature but something is really bugging me : if we're fighting against siloed data, how come we can't have account level database (like the beta) and then decide which spaces have access?

From what I've tested, duplicating a table to another space creates an independant table so updating one won't update it's duplicates. This prevents from having an unified data architecture and utilizing the tables in account forms (and probably other features/use cases).

Does the API connexion solves this by linking all spaces to one external source?

I find this to be a major setback from the beta.

Any help/workaround is appreciated.