Exciting news ! ReportServer 3.1.0 will include support for Google BigQuery datasources!
Google BigQuery is a serverless, highly-scalable, and cost-effective cloud data warehouse with an in-memory BI Engine and machine learning built in.
Even your beloved pivot reports for dynamic lists will support BigQuery datasources, since these use the existing JDBC mechanisms of ReportServer!
Keep tuned and happy reporting!
Your ReportServer Team