Apple doesn't have that kind of clout. If a retailer decides it doesn't like Apple's terms it can still sell cell phones. A developer can develop for other OS's. Apple, unlike MS, can't leverage its position to force out competitors like MS could and did.
Apple have never had that kind of clout with the Mac, but they
absolutely have that kind of clout in the phone market - something like a
1/3 share of active users - you don't need a 95% market share to be able to distort the market.
Anyway, Apple are not on the EU "gatekeeper" list for
selling phones - they're on it because they control iOS and a bunch of services that are linked with their phones - not least the App Store. Google Play Store and Apple App Store together account for the vast majority of the
"mobile app store" market, with Apple a long way ahead of Google.
(It's interesting to note that, even though Android has
always supported 'sideloading' and independent app stores, Google Play is still massively dominant on that platform... so its not clear why 3rd party app stores on iOS would bring about the iPocalypse)
...so, in reality, although Android gives you a choice of hardware, in terms of App Stores, the choice is still only between Apple and Google - Google who
also provide search facilities for iOS and are one of the main providers of email and personal productivity apps (alongside Microsoft, who are
also on the naughty list). Google have
already been fined by the EU for telling "independent" manufacturers that they can could use the Play Store if they agreed to bundle Google's productivity apps.