Do I need to use Google Payments?

Question

Google

I'm going to make applications for Google play, in it a currency is bought for money with which you can perform certain actions in the application, the amount of this currency in the account can be increased (earned), the currency can be withdrawn by converting it back into money. So the question is, what is this "currency" (I think it's just a unit of measurement, or something like that, is it?), and whether you need to use a Google payment aggregator to buy it, or can any other?
Ps This is not a game of chance, and not just a game.
This currency was made for convenience, it does not carry any privileges, it would be possible to do without it. But it is more fun with it)

Answer 1

if there are purchases - money can only be used for InApp
exceptions - low-margin, such as physical goods