It is not clear what this really means.
GOG Galaxy

GOG announces that their GOG GALAXY 2.0 client now includes "official" support for Epic Games Store integration. It is not very clear what this means though since their cross-store client already supported games from the Epic Games Store.

Maybe their official announcement for today's update will shed a bit more light on what is going on.

We’re happy to add to GOG GALAXY 2.0 the official integration with Epic Games Store, which is the second most connected external platform in the app, says Oleg Klapovsky, SVP at GOG. Together with GOG.COM and Xbox Live, those official integrations are bringing a more seamless and reliable experience to gamers.

We’re excited that Epic Games Store integration has come to GOG GALAXY 2.0, said Steve Allison, General Manager of the Epic Games Store. It’s an important step towards breaking down walls between PC stores, as it enables a unified experience for players to manage their PC games library independent of where their games were purchased.

The new official integration is the latest addition to GOG GALAXY 2.0, which we’re constantly improving with features requested by gamers. One of the recently added was the ability to see all your gaming subscriptions in one place. It helps gamers to conveniently browse, install, and launch games from an overwhelming amount of titles available on each subscription.

Check this and other cool features present in GOG GALAXY 2.0 by downloading the app on Windows or Mac from www.gogalaxy.com.