Thanks for the detailed reply — super helpful!Quick follow-up:
Could you walk me through how to either (1) create that manual tax override in Shopify for the class product to always apply Quebec taxes, or (2) set it up using custom tax logic like you...

I offer an in-person service based in Montreal, Quebec, Canada. Occasionally, clients from outside the province travel here to attend my classes. However, Shopify only collects taxes based on the customer's billing address — meaning it sometimes does...