UPDATE 2019-11-15
In the last 3 weeks I (nearly) finished the complete order handling for store merchants (ProcessWire backend). This includes the following features:
search for orders
filter orders
extensive overview of all order details
download of invoices
resend invoices to customers
refund amounts to customers
... all right from within your ProcessWire backend!
That doesn't sound like much, but it was a good piece of work. ?
Here is a short clip to demonstrate the new features: