What, specifically are you looking for?
How many invoices you wrote for Payee Name = Acme Anvils?How many "Widgets" you sold to how many customers?
More details, please.
What category are your "Widgets" allocated to?
Please try this:Itemized Categories report.Customize to select only the Customer Invoices account and the category of your "Widgets".Sort by Description (customer name).
This may not be exactly what you're looking for, but it's as close as you can get.