it is documented here: https://docs.microsoft.com/en-us/azure/databricks/sql/admin/sql-endpoints#sql-endpoints-name-changed...

With 2X-Small size you allocate 1x Standard_E8ds_v4 for driver and 1x Standard_E8ds_v4 for worker.

When configuring a SQL warehouse you can chose between reliability optimized (=full price VMs) and cost optimized (=spot VMs for workers).