The last condition, in principle, is not necessary, unlike Apple, it is rather a recommendation from Google, since users have great confidence in applications hosted on Google Play. You can distribute your Android application yourself in any convenient way.
In the case of the iOS platform, Apple's position is stricter and does not allow the distribution of applications bypassing the App Store. The ability to distribute your iOS application directly exists for Apple Developer Enterprise-accounts, the payment for which is about $300 per year. This type of corporate account is intended for distributing applications within the organization.