We're unable to import the attachments in QuickBooks Online. You'll want to manually attach the documents/pictures in each transaction.
Open the transaction.
Choose a document/picture, then click Open.
Click Save and close or Save and new.
I also suggest sending feedback. If you don’t mind taking a few moments to provide your idea to our product engineers, we would really appreciate it. This will help us improve our product and services. You can do that by clicking the Gear icon, then choosing Feedback.
Don't hesitate to reach out to us if you have other questions.