IOSS (EU VAT payment) support for Canada Post labels?

Question for Canadian sellers to the EU: I am now charging EU VAT at my checkout (called IOSS) and remitting through a third party app (easproject.com) However Shopify does not allow me to purchase a Canada Post label with an IOSS number attached. I have to do it through the Canada Post website. Carrying the information over is pretty tedious. I'm wondering if anyone knows of a shipping app that lets you buy IOSS enabled Canada Post labels, and ideally also integrates with Etsy. I'd love to be able to do all my labels in one interface. I'm open to a Shopify app or third party website if necessary Thank you!