Help Needed: Migrating ETL from Power Query to Python (PyCharm) - Complex Transformations

I’m working on migrating an ETL process from Power Query to Python (using PyCharm) and need advice on handling complex transformations. Our current Power Query setup struggles with performance. The Fact has over 6 milions rows. Data sources are on Sharepoint ( csv, xls).

What Python libraries work best for replicating Power Query logic (e.g., merges, appends, pivots, custom M-like functions, compounds key)?

There is no access to SQL, is Python the best tool to move on? Any recommandations and advice?