There’s what we want, and what works in the here and now.
Shopify has no concept of multiple skus per item, nor most platforms, services, software or systems. Shopify isn’t even realy single-sku centric /shrug.
Make sure to submit a feature request to a shopify support advisor.
And lots of businesses run different domains|stores for different regions even on shopify when the markets feature can fill all the needs.
So multiple variants/products is the only sane way currently to have SKUS sanely exposed throughout out a business either in it’s shopify store/admin or it’s off-shopify processes.
For the frontend, online-sales channel theme, to avoid messiness and confusing customers you’d customize the theme to provide the right context.
Example alternative to show why insisting on not having different variations creates fragile business processes: Use metafields and some advanced theme customizations to show the proper sku to the customer and in the order as order attributes… but that will only go so far as the online-sales channel theme and not really work for multichannel.. nor work for backend processes like fulfillment.
So for backend processes you would still consume the original sku property on the variant that went through the order unless you also setup automations to edit orders and attach the variant with the proper skus BUT that means that variant with the proper sku already exists so why have these hoops at all.