Power BI's two best kept secrets: the PBIRS REST API and Power BI REST API

PBIRS REST API (public, completely customizable API)

If you use PBIRS to publish PBI reports to a centralized portal, or just want the ability to programmatically control your PBI development, deployments and system maintenance, there is a PBIRS API that you may not be aware of that can supercharge your PBI development environment.

It is not published but it is completely documented on SwaggerHub.com

It bears a close resemblance to the original SSRS v1 and v2 APIs, but in addition to all the SSRS functionality, it provides functionality for managing PBI reports, data sources, PBI data refreshes (data is refreshed on demand in SSRS reports), scheduling of PBI reports, managing uploaded ExcelWorkbooks and many other really useful features that developers can leverage to get the most out of your Power BI environment.

Publishing, updating PBI reports, data sources, posting ExecutionLog entries and more is made available via the PBIRS API

Power BI REST API (MSFT proprietary API)

And then there is the all-powerful Power BI REST API which serves as a successor to the ReportExecution2005.asmx and ReportService2010.asmx Reporting Services SOAP APIs that the original SSRS REST API was built upon. 

This API is not publicly documented (the SDKs are, however, which suffices for most usage scenarios) and not as extensible as original the SSRS REST API (ie. you need to authenticate with Entra and an online MSFT Power BI account; no custom authentication is possible), but it provides most all of the abundant paginated report and data source functionality in the original SSRS SOAP API along with a cornucopia of new API operations for managing Power BI users, workspaces and content.

The following is an example of using the Power BI REST API with PowerShell (using the MicrosoftPowerBIMgmt PowerShell module, if connecting via .NET you'd use the Microsoft.PowerBI.Api .NET library/Nuget package; an example of using the Power BI REST API in .NET can be found here):

This demonstrates getting a list of PBI workspaces, reports and getting an individual PBI report by name

With these two APIs organizations can continue to manage their SSRS/PBIRS environments and start managing their cloud-based Power BI environments- programmatically.

References: 

https://app.swaggerhub.com/apis/microsoft-rs/SSRS/PBI3.0

https://learn.microsoft.com/en-us/rest/api/power-bi/reports 

https://github.com/Microsoft/PowerBI-CSharp

https://github.com/microsoft/PowerBI-Developer-Samples/blob/master/PowerShell%20Scripts/Export-PowerBIReport.ps1