I know we are in touch separately but I thought I would just add a note for completeness here.
Online marketplaces are the Amazon’s, eBay’s and AliExpresses of the world. They are platforms that aggregate products from multiple sellers and facilitate a sale to a customer. Many countries have introduced rules for VAT/GST (and even sales tax in the US) that puts the responsibility on the online marketplace to collect the relevant tax and pay it to the tax authority.
Providers like Shopify that enable the platforms for individual ecommerce sites should not be online marketplaces. They provide the infrastructure for individual businesses to sell directly rather than aggregating products from different vendors.
Indirect Tax Solutions