I have resorted to put all source reports in a SQL database and run power query transformations within the flow definitions. This turned out to be a good and effective way to automate our processes.
Unfortunately Flow is very slow to generate Excel files as they are added line by line into an Excel table (roughly 100 lines per minute I noticed). If you have thousands of lines generated it will not be a great idea.
@SSM-SPARX So you are dead on, on the generation of excel files...Excel connector has been nerfed so bad by Microsoft that unless you are generating a few thousand lines, you will be waiting hours.