Yes, Athena is the serverless data querying alternative to BigQuery, not Redshift. When I used Athena for some large scale data querying just a couple years ago

Yes, Athena is the serverless data querying alternative to BigQuery, not Redshift. When I used Athena for some large scale data querying just a couple years ago it was extremely slow, like two orders of magnitude slower than BigQuery for the same queries. And the UI, documentation, and just general user experience is nowhere near as good as BigQuery's. Nothing from AWS competes with BigQuery, it's genuinely a good product.