Haven't seen any posts about this and it's a pretty big thing. From DMA website:

Examples of the “do’s”: gatekeepers will for example have to:

• allow third parties to inter-operate with the gatekeeper’s own services in certain specific situations;
• 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.

Example of the “don'ts”: gatekeepers will for example no longer:

• treat services and products offered by the gatekeeper itself more favourably in ranking than similar services or products offered by third parties on the gatekeeper's platform;
• prevent users from un-installing any pre-installed software or app if they wish so;
• track end users outside of the gatekeepers' core platform service for the purpose of targeted advertising, without effective consent having been granted.

We'll see how this plays out but this is first move in a very long time that could open up platform like WhatsApp to 3rd party clients and force Google and Apple to open their mobile OSes to other apps. Maybe we'll see stock Android without play services? One can dream...

P.S. https://digital-markets-act-cases.ec.europa.eu - page about the legislation