Which upsell or cross-sell app works with Shopify multiple currency checkouts?

As far as I know, the only upsell or cross-sell app that works with multiple currency checkouts is Blod Upsell, Bold Multi-Currency, using Cashier as the checkout.

I agree that Bold Upsell is a great tool for what you are looking at doing.

Shopify features multiple Shopify upsell app that works with various currency checkouts. Some recommendations include:

1. ReConvert Upsell & Cross-Sell
2. Frequently Bought Together
3. Bold Upsell

All these apps support the multi currency check out Shopify.

Alternatively, there are Shopify multi currency apps that you can use, such as Multi-Currency Checkout+. You don't have to suffer from the confusing built-in multi-currency transaction feature in Shopify anymore.