Hello there, 3DDoors.

I appreciate you for getting back to us here in the Community. I'm here to share some information about e-signature on an invoice. 

Capturing signatures on an invoice is available in QuickBooks Online (QBO) mobile app. However, there's no option to add bundled inventory items to the app.

In the meantime, you can use a browser on your phone to add bundled items to an invoice. Once done, use the mobile app for e signature.

You can also check this article for more information about comparing mobile app features. For more useful topics, feel free to browse them here on our Community page. 

Feel welcome to get back on this thread if you'll need assistance in dealing with your invoices. We're always here to help you.