What actually changed
The integration lets you tag @Google Business Profile inside a Gemini conversation and ask it to draft updates to a listing: hours, services, photos, the rest of the listing fields. Approved changes go out through the official Business Profile APIs and pass the same verification the manual editor applies, so this is a drafting surface rather than a side door into the listing.
Two limits were in place from the June 10 launch. Availability was partial, and one account could work with one profile. The August bulletin clears both, except that the single-profile restriction still applies to setting up a business notebook. The Workspace limit is untouched, and Google describes support for it as in the works without giving a date.
What to do about it
Check which account owns your listings before planning around this
Ownership of a Business Profile tends to be an accident of who created it, and on older listings that is often a personal address rather than the company domain. If your profiles sit under a Workspace account, the feature is not available to you yet and no amount of setup will change that. If they sit under a personal Gmail nobody has migrated, you can use it today, and the ownership question is one to settle anyway.