Can you tell me more about these apps or items that you're referring to? That will help me provide you with an accurate solution to this concern.
If you're referring to apps or a third-party app that can work with your items, you can check our QuickBooks Apps store and browse for an app from there. However, it would depend on your region for the availability of the apps.
However, if you're trying to find a way how to add your items (products or service items), you can do it from the Products and services page.
Here's how:
Go to the Gear icon and choose Products and Services.
Click the New button.
Choose the Product/Service information.
Provide all the necessary information.
Click on the Save and close button once you're done.
For detailed steps on how to add or edit a product or service item, refer to this article: Add product and service items to QuickBooks Online. That will also guide you on how to add services and products you don't plan to track inventory.