Hello there, @james-malia-wyma. I want to share some details and alternative solutions for moving your data.
Currently, Invoice2go and QuickBooks Online integration isn't supported yet. Therefore, an option for a direct way to transfer your client list is unavailable.
As a workaround, You can follow the suggestion provided by Fiat-Lux ASIA, which includes exporting your data from Invoice2go and then using a third-party importer tool to import the list into QBO. This will allow you to transfer your desired information effectively.
I'd also recommend contacting Invoice2go in case you'll have issues with exporting. This allows them to provide further information and tips to have this done seamlessly.
If you're all set, feel free to read this guide for you to learn more about billing your customers: Create and send invoices in QuickBooks Online.
Feel free to drop by if you need anything else. I'll be around to lend a hand. Stay safe!