Hello, Mcramer80.
Let me share some insights about your request.
The option to automatically create an invoice from a purchase order is currently unavailable. The workflow would be to create a purchase order, add it when you create a bill and make the bill billable to the customer. This way, you can create an invoice from the billable expense linked to the customer transaction list.
Here are some sample screenshots for the workflow:



You can send a suggestion to our product developers. They'll review this idea and might consider updating the purchase order feature in the future.
You can follow these steps to send feedback:
- Go to the Gear located at the top.
- Under Profile, click Feedback.
If you want to check the status of your request, you can click this link: Customer Feedback for QuickBooks Online.
To learn more about creating a purchaser order, or entering a billable expense, please feel free to read these articles:
If you have any follow-up questions or other concerns, please don't hesitate to let me know in the comments. I'll be around to help you out again. Take care.