Hello there, @Jambotwiga.
The access portal for customers to view their invoices and pay them is currently unavailable in QuickBooks Online (QBO).
I know that having a customer management access portal for customers to view their invoices is beneficial to your customers. While this option isn't available, I suggest submitting feedback directly to our product engineers. They may look into this suggestion further and consider adding the option in QBO.
To submit feedback, you can go to the Gear icon and select Feedback. Then, enter your suggestion and click Submit Feedback.
You can also visit our Customer Feedback page. This will help you track the status of your product request and get the latest updates from our developers. Updates such as how the recent enhancement made to QBO helps our business owners, like you.
Please touch base with me here for all of your QuickBooks needs, I'm always happy to help. Thanks for dropping by.