Application to edit data source for a Power BI report

I want to create an application that allows clients to edit data that sits behind a power BI report. The data involves multiple tables and some of them can have up to 1 million rows.

The function of the application would be fairly more complex than anything I’ve built in power BI or Python (my main tools). It would need to have the ability to select a group of rows from the table, based on inputs from the client, and then allow the client to change the value in a specific column. Further complexities would be allowing the client to see how each change affects the outcome of the whole table (parts of the table would have to be recalculated based on this change) but that’s further down the road.

What tool should I use to build this application?

I am unfamiliar with Power Apps but I’ve seen there is a hard row limit that is incompatible with the amount of data I would have to put into it.

Thanks.