Hi
In Power BI, it supports to connect to the data source which use oAuth2 authentication, for example, SharePoint Online. So in your scenario, which kind of data source do you want to connect to in Power BI? Scheduled refresh is available in Power BI Service not in desktop.
As you mentioned "I created an app that pushes the data into Power BI using the REST API", do you mean Power BI rest API or another knid of API? If we connect to the data source in Power BI Desktop, we are able to perform modeling for data.
In your scenario, would you please share more information about your requirement, so we can understand it better?
Best Regards,
Qiuyun Yu