Earlier quoted context omitted.
On Android there is the F-Droid software repository, and there is no issue of competition with the Play Store. Would things be different on Apple phones?
Developers can safely ignore the F-Droid store because it represents no significant market share. This will not be true of the stores that Epic, Facebook, and Google, and Amazon et al would start up on iOS.
https://www.businessofapps.com/news/amazon-app-store-vs-goog...
Interestingly, there appears to be more revenue made per user on the Amazon store than on Google Play:
https://www.mobilemarketer.com/ex/mobilemarketer/cms/news/re...