> Yes, on the most recent Android, there is no monopoly.
> On anything else, it's there.
Alternative app stores for Android have existed for a long time. Samsung Galaxy Store, Amazon, Huawei AppGallery, F-Droid, Aptoide, etc. They are also available for older versions of Android.
It has been working for over a decade. All you have to do is install the third-party app store's APK, and give that app permission to install or update apps.