Power BI Service (Mac) Create Reports from Transformed Data

HI emgee 

You're right you can't run Power BI Desktop on a Mac natively, with a standard Pro licence this is a severe limitation as you found as no Data Modelling facilities exists outside of Power BI Desktop. However with a Premium Per User licence (PPU) you will be able to build a Datamart, this (finally!) allows Data Modelling in the browser and does not require Power BI Desktop. You should be able to get a 60 day trial of a PPU licence so you can try Datamarts out. 

see: Introduction to datamarts - Power BI | Microsoft Docs

If you don't go the PPU route, you option is to use an Emulator (Parallels?) or similary to run Power BI deskyop on a mac.

See: https://www.youtube.com/watch?v=qUpqtWEOG40 (but note this video pre-dates Datamarts)

hope this helps

Stuart