Here are the steps to create Bundles and Bundle Items using Dataloader (Fields marked with Star are required fields, rest are optional depending on the business use case) –
Once the bundles are uploaded successfully; the resulting file will have a corresponding Salesforce id for the bundles. Use this id to create a Bundle Item file in csv format. See the template below as a starting point
Here are the sample Excel files for Bundle and Bundle Items upload (Please ensure to conver it to CSV format)
Notes –