Doesn't really matter: if you are making a phone app or service (especially one that has any sort of network effect), you need to support both ecosystem which means you must submit to Apple's ukases.
That player also has a history of tracking, fingerprinting and privacy violations that not everyone is comfortable with, especially relating to a device that has as much control over you as a smartphone.
it is not like these 2 products were identical except for sideloading.
They don't have the same hardware, Apple has an unlimited ad budget, if you want to chat with somebody using iMessages, you are pretty much limited to iOS, you can't transfer app purchases between platforms, etc
If you go into subscription settings on iOS devices, they show a "try out apple music" ad -- you think this position is available to Spotify/others? They don't pay 30% on top of sales to boot.
Same thing with Google, they cross promote their own new properties everywhere in Gmail (left pane) and Google.com but no one else has access to those locations, they can destroy thousands of small business through this practice.
Honestly it is almost funny how Google has been mostly unable to successfully launch new products while they have the capacity to promote them to virtually all of the global north.
In particular with Play Music .. not going to complain, I don't think that this market needs another FAANG product but wow, failing to promote that service is one epic blunder.
Instead of choosing that product, many people here complain that the other company doesn’t give them what they want.