Can BYOB support Shopify Markets?

Variant mode: No
Discount code mode: Yes

From the limitations,
You can't edit orders placed in a currency other than your default store currency (unless you use Shopify's B2B feature). Although you can't edit the order, you can refund the order, then create a draft order and email an invoice in your customer's local currency.

Our app is based on the order editing API. If you're using a price discount for your bundles, these foreign currency orders can't be edited. As a result, the individual items cannot be added and the inventory cannot be updated. The base currency orders are ok though.

A workaround is to use the discount code mode, where a bundle is paired with a discount code, and no order editing is required. The individual items are added to the cart instead. But a price discount is not supported under this mode.