Promo codes for in-app purchases?

Question

Google Play

15 minutes of googling to no avail. So the question is appropriate.
Is it possible to distribute in-game bonuses for free (which the user usually buys with his own money) through the google play api? For example, through promo codes? Or manually by id or in some other way?
For example, I want to push the game through crowdfunding. More in order to set the first installations. As a reward for charity - in-game bonuses. That's what everyone does.
But I have met many times with a situation where developers do not give out the promised prizes for contributions. Even when these contributions reach colossal sums. The simplest conclusion: google play does not allow promo codes for in-game purchases.
If the functionality is available - pliz, give a link to the api.