Not quite sure what you mean by "output to Databricks SQL directly". DLT currently cannot write to Unity Catalog. The target schema name you specify in DLT pipeline settings currently becomes a Hive Metastore database and it will be created by DLT if it doesn't exist.
It sounds like what you are trying to do is:
You have an existing HMS database named "poc" with location set to "dbfs:/..../poc.db" and you would like to use this database as the target schema in your DLT pipeline. I see no reason why you shouldn't be able to do this. Based on the error message, it looks like either the database path is incorrect or it has special characters that are not allowed.