Examples of the “do’s” - Gatekeeper platforms will have to:
allow third parties to inter-operate with the gatekeeper’s own services in certain specific situations
allow their business users to access the data that they generate in their use of the gatekeeper’s platform
provide companies advertising on their platform with the tools and information necessary for advertisers and publishers to carry out their own independent verification of their advertisements hosted by the gatekeeper
allow their business users to promote their offer and conclude contracts with their customers outside the gatekeeper’s platform
The interoperability is the big one. The Fediverse gives a way for Meta to be in compliance, and they have an interest in maintaining competition.