It's said in the DLT documentation that "pivot" is not supported in DLT but I noticed that if you want the pivot function to work you have to do one of the the following things:

1. apply the pivot in your first a dlt.view + the config "spark.databricks.delta.schema.autoMerge.enabled: true" .
2. apply pivot outside of dlt decorators then start using the output in dlt.view or dlt.table.

Note: I noticed that this works but you get a warning saying that `GroupedData.pivot` function that will be deprecated soon, you will have the same warning if you use Collect for instance.

Hope that help!