Hello,
You can force the plugin to think that a currency has a specific exchange rate using some custom code that you can put in a PHP file and activate it like a plugin.
A full example is here:
https://gist.github.com/alex-georgiou/492196184f206002c864225180ca8fbb
The example declares two custom currencies in the exchange rates system, and also sets a few exchange rates.
This will allow the plugin to show equivalent amounts in other currencies below the actual amounts. You can also have customers checkout a woocommerce cart with custom currencies, if the exchange rate is known between that currency and the shop’s default currency.
Please let me know if you have any questions about this.
with regards