EU law doesn't actually require a monopoly for competition rules to apply, it's a "dominant position". Apple certainly meets that definition for smartphone platforms.
https://eur-lex.europa.eu/EN/legal-content/glossary/competit...
https://eur-lex.europa.eu/EN/legal-content/glossary/competit...
And on the iPhone, you MUST use the Apple App Store, not just as a means to distribute your app, but as your payment provider. You can’t collect payment details yourself, use Stripe, Paddle, anything. You MUST use Apple.
You simply cannot enter business without paying Apple a share. That’s a monopoly.