So i'm currently using Auto Multi Currency Conversion (Its great!), the only issue is that when choosing a different currency, it applies to the entire site EXCEPT for any products displayed via an upsell app. I've tried a number of different upsell apps, and all products appear in the default currency regardless of the currency selected.
Anyone know of any apps that work together to avoid this problem?
I think you should have a look around this writing: 37+ Best Shopify Upsell Apps. 37+ Best Shopify Upsell Apps from hundreds of the Upsell reviews in the market (Shopify Apps Store, Shopify Apps) as derived from Avada Commerce Ranking which is using Avada Commerce scores, rating reviews, search results, social metrics.
Hope it's useful for you
Most upsell apps load the products asynchronously which is usually why they don't work with currency converters.
You can try reaching out to the currency converter app developer and your upsell app developer to see if they could find a solution.
You could also try using Shopify Multi-currency: https://help.shopify.com/en/manual/payments/shopify-payments/multi-currency/setup
I've found this tends to work with apps without needing to change much code.