@Michael_Soprano For Orchestrated Campaigns, the dataset should be enabled for Orchestrated campaigns before ingestion. The usual order is: create the relational schema, define the primary key and version descriptor, create the dataset, enable it for Orchestrated campaigns, then ingest the data.
Data Landing Zone is supported as a source for Orchestrated Campaign ingestion. For file-based ingestion, Adobe supports delimited/CSV, JSON, and Parquet formats. For Campaign Orchestration CDC ingestion, make sure the file includes _change_request_type with lowercase u for upsert or d for delete.
If the dataset is not showing during dataflow setup, I would check whether the dataset is based on a relational schema, has a primary key, has a version descriptor, is enabled for Orchestrated campaigns, is in the same sandbox, and is not already tied to another dataflow. Adobe also enforces a 1:1 relationship between a dataset and dataflow.
Ingest data for Orchestrated Campaigns: https://experienceleague.adobe.com/en/docs/journey-optimizer/using/campaigns/orchestrated-campaigns/data-configuration/schemas-datasets/ingest-data