@demo-user Serverless SQL Warehouses and the Express account type are designed for simplicity and rely almost exclusively on the cloud provider's secure identity mechanisms.

• Serverless SQL Warehouses (and Serverless Jobs) do not currently support configuring generic S3-compatible endpoint URLs and access keys
• Complex, non-standard cloud integrations are often limited or unsupported compared to the Enterprise account type

The only reliable and supported way to connect to a generic S3-compatible object store using a custom endpoint and access keys is by using Provisioned Compute where you control the Spark configuration.

Thank you for your response! Are Spark configurations enabled on Enterprise accounts with serverless compute? I am getting errors when I attempt the Spark configurations 

Serverless compute does not support setting most Apache Spark configuration properties irrespective of Enterprise Tier as dB fully manages the underlying infrastructure.