You can already set different prices for different regions if you use Shopify Payments: https://help.shopify.com/en/manual/payments/shopify-payments/multi-currency/international-pricing
Does the beta fix work with 2 Amazon FBA location countries? - different Amazon Seller ID in each country
In my case Amazon FBA provides inventory quantities to Shopify and fulfills Shopify orders in both Canada and the US.
FBA US inventory is only available for US addresses (sales in USD by US legal entity)
FBA CA inventory is only available for CA addresses (sales in CAD by Canadian legal entity)
Currently running 2 stores to deal with this but would prefer to upgrade to Shopify Advanced and only have 1 store.