Hi there, @PO in app.
Thanks for sharing your concerns with us. At the moment, sending the purchase order in the mobile app is currently unavailable.
I appreciate your idea on this and I’ll make sure to send this feedback to our developers. In the meantime, you can submit feedback yourself by going to the gear icon and selecting Feedback.
I am also including this article for your reference about the mobile features in QuickBooks Online: Compare mobile app features.
I'd be here to get back and help if you have any other questions. Take care!