Currently Microsoft offers the MCSA: BI Reporting certification to measure Power BI (and Excel BI) skills. But for PowerApps no such certification exists. As PowerApps and Flow become more of an independent solution, capable of interacting with more than 250 services, it seems reasonable to create a seperate certification that measures these specific skillsets. Somehow, if you are a PowerApps or Flow Ninja you do not have anything to show for it.
We cannot expect the ordinary Power User, who is the primary focus of the Business Application Platform, to earn a SharePoint certification to proof that he or she is capable in PowerApps. That would seem quite unlogical. And secondly, a lot of Power Users use PowerApps in combination with 3rd party services other then SharePoint.