Google Ads makes it possible to post ads that you only pay for when the user has for example made an in-app purchase. This is made possible by integrating your ad campaign with an analytics provider that learns about the conversion through the app.
Google already supports several providers that appear in its list:
It is possible to become a provider by adopting the API which is documented here:
I'd love to see that added to Matomo!
That be great indeed. If someone is keen to work on this we're happy to help.