There is not. If you were to add a currency symbol then the value would no longer be a number and pie charts only work with numbers.
Consider going to https://ideas.splunk.com to make a case for supporting currency symbols in pie charts.
Is there a way to change the display label of both texts? Right now, both the first row and 2nd row is totalFeeAmount(USD), but I want to change the label of the percentage value to totalFeeAmount, aka get rid of the (USD) part coz it's not USD