It looks like the EU has decided that the iMessage market specifically is not one where gatekeeper status comes into play.
iMessage isn't popular enough with businesses to force interoperability.
arstechnica.com
So it was the threat of legislation rather than actual action that may have moved the needle on RCS ever so slightly. It's a tricky thing to measure as a) Apple isn't going to fall over themselves to give up how their users actually use iMessage and b) even though the protocol/app are used when a fallback SMS message does arrive at an iOS device, the EU feels that the iMessage-only use falls under their threshold at the present time. I get the complexity here. Every iOS user (within rounding error) in the US is an iMessage user, but it's not fair to count every iOS user in Europe as an iMessage user and those few who do use it, you want to count users not devices as you can have an iPhone, iPad and Mac or whatever.
To be fair, iMessage in Europe is like WhatsApp in reverse. You'd use it to talk to Americans or similar who don't use WhatsApp, and that's pretty much it. The number of users is probably at or close to the threshold, but if it's not EU-citizen to EU-citizen communication, they are likely to err on the side of not regulating.
Other Apple products like the App Store are still very much affected (as is Google Play etc.)