If you are playing crypto slots from a well-known provider that uses cross-currency betting interfaces, then the RTP on the virtual currency and real-money versions are the same. For example, Endorphina casino games accept BTC, ETH, LTC, DOGE, USD, UKP, INR, CAD, AUD, CAD, EUR, ZAR, and more currencies. You can see this is a mix of crypto and fiat currency. However, the same slot game will load with the same RTP with the only difference being the currency accepted.