What are the marketing agencies for promotion in the App Store, working for a percentage?

Question

Marketing

I have been looking for a marketing agency to promote a paid application in the US and European App Store for about a month now. The key requirement for me is that they work for a percentage of the sales, because for me there is no guarantee that the money invested will pay off, or at least that the agency will earn their money, and not just send out press releases.
Hence the request - if anyone knows such an agency, then I beg you to advise me. Thank you!

Answer 1

Nowhere, no one works for the wind, you suddenly decide to delete the application and that the agency should suck its paw and just write off the money spent on your company as a loss or what?
Such things are only done in private or out of friendship.