Google play. Using third party payment systems?

Question

Google

There is an application for Android. It is necessary to organize the replenishment of the balance in it.
I don't want to use payment via Google for two reasons:
- There is no way to set an arbitrary amount
- A large commission
It would be ideal to connect Webmoney Merchant, etc., but, as far as I understand, Google prohibits the use of third-party payment systems.
Is it so? If so, how can I top up the balance for an arbitrary amount?
An iOS app is also planned, are there any restrictions there too?

Answer 1

Is it so?

So.
Personally, I have not seen a single application either in the Google store or in the Apple store that allows you to do this. In any case, Google technical support will give you the most accurate answer to this question.
Exactly the same restrictions.

Answer 2

Replenishment of a separate site
through the application is impossible
in the application to pay from the balance of the site

Answer 3

See how movie ticket buying apps work. For example, Kinokhod offers payment by bank card, and the rambler cash desk generally offers to pay via paypal.