Google has an alternative at least (can download other app stores, apks, and have been able to for 15 years), I have no idea how Apple has been allowed to get away with what they do.
Also in the worldwide market it most definitely isn’t a monopoly in phones at all- which is exactly why the EU had to reform their laws (DMA ect)to get regulatory powers over them.
They also play this trick where they pretend the only market is "phones" and ignore all of the complementary markets they're tying together with their phones, like app distribution and browser engines etc., since the market definitions for those shouldn't be the same as it is for "phones" when an app store that can be used on Google and Samsung phones can't be used (and therefore doesn't compete) on Apple phones and vice versa.
The "App Store" is just a natural extension of the club. As far as I'm concerned, they can gatekeep and sloppify as much as they want. Apple users agree to this.
I've never felt slighted that I couldn't hack apart my iPad - though I will absolutely do it once somebody cracks the code and gets a proper Linux kernel running.
If by "club" you mean Apple's digital fiefdom.