Hey @iislam2907!
You can get some SQL queries from the internet which can help you build a basic funnel using the exported data. Pretty sure there will be some Tableau templates for funnel analysis as well.
But from what I know, trying to replicate the Amplitude funnel analysis chart with all their clauses will be a tough task ( if not impossible ), given the way Amplitude crunches data on their backend engine.
If you are storing the costs data in GCS, the easier way will be to ingest that in Amplitude and conduct the analysis in Amplitude if that requirement works out.
Would love to hear from the SQL geeks in the Community if they have attempted such a task.