Apple implemented strict rules about tracking and privacy that cost Facebook 12 billion dollars:
https://www.forbes.com/sites/kateoflahertyuk/2022/04/23/appl...
I, as a user, think that's great.
The Google play store has no similar anti-tracking rules. Why? Well, partly because those rules would negatively impact Google, but also because Meta could credibly decide to move their apps off the play store and onto their own "Meta Store: The only place to get Facebook, Instagram, Threads, and WhatsApp".
If it was easy for Meta to set up their own store for iOS, they absolutely would because currently Apple kneecaps their ability to track and sell user data in ways that costs Meta REAL money.
Google does not exert the same kind of control over the play store, so Meta is quite happy to keep Facebook there.
So, as things stand (with a closed iOS ecosystem) I can use an Instagram app on my phone that's subject to a bunch of pro-consumer rules about tracking and data protection. If iOS allowed third party stores then I would almost certainly not be able to do that any more.