We have multiple Point of Sale software that support QuickBooks Online. You can click here to get an overview of the available apps and how it works. Just a heads up, the apps are limited to these countries:
United States (US)
United Kingdom (UK)
If you're ready to get the app, just select it and click the Get app now button. If you already have one, for the integration and mapping, I would recommend contacting their Support team.
Let me know if you have other questions. Take care!