At this time, importing a transaction list in QuickBooks Online (QBO) is currently not possible.
As a workaround, I suggest finding a third-party that offers this function.
You can look for a third-party app inside your QBO account by following these steps:
1. Click on Apps on the left side of your screen.
2. Search for an app or browse by app category by clicking the drop-down arrow.
3. Select an app, then click Get App Now.
Let me know if there’s anything else you need. I’ll be around to help you.