You need to recommend a strategy to consistently define the business unit, department, and product...

Create a shared dataset for each standardized entity.

Create dataflows for the standardized data and make the dataflows available for use in all imported datasets.

For every report, create and use a single shared dataset that contains the standardized data.

For the three entities, create exports of the data from the Power Bl model to Excel and store the data in Microsoft OneDrive for others to use as a source.