Is there a way we can make QuickBooks Online Purchase Orders look more company-branded?

Yes, that's definitely doable. However, you'll need to do that in QuickBooks Online. Any styling updates you make in QuickBooks Online will be reflected in all POs generated via ApprovalMax.

To put it simply: QuickBooks Online handles the "look and feel" of the document, while ApprovalMax handles the "content." Once a Purchase Order request is fully approved, ApprovalMax sends the relevant data (such as vendor details and costs) to QuickBooks, which then generates the actual document using the branding you’ve set up.