Hi Wondering in Wichita,

Thanks for sharing your concerns with us. At the moment, sending the purchase order in the mobile app is currently unavailable. 

I understand the need for having this feature in QBO and this is a great idea to add in the program, so I'm personally taking note of this suggestion and send it to our developers. This helps them in deciding on what features might be added in their future product updates.  

Furthermore, you can login on your mobile web browser to create and send your purchase order. 

You can also check on this article for your future reference: Compare mobile app features.

I'd be here to get back and help if you have any other questions. Have a nice day!