Hello @paulh,
Thanks for posting in the Community. I'm here to lend a hand with importing data into QuickBooks Online (QBO).
Just to clarify, when you mention exporting your data to a QuickBooks Online format, are you referring to uploading your data into QBO from Enterprise? If so, your data from Enterprise should be available in your Online account. For additional information on this, I'm including an article that covers this process: Convert QuickBooks Desktop File to QuickBooks Online. You can locate specific instructions for your software in the QuickBooks Desktop Enterprise files section.
If you're needing to import other data into your QuickBooks Online account, such as list data, please refer to the following links:
Since you're switching to QuickBooks Online, I want to make sure that you have the resources to get the most out of the software for your organization. You can locate tutorials designed to help a user become accustomed to the software here: QuickBooks Online Tutorials.
Should you have questions about the migration or anything else, please let me know. Wishing you a wonderful day ahead.