Less hassle since users will not input the purchase amount and so on.
Over 20 different fiat currencies
I saw this info in playstore, where could we see the specific list of fiat currencies included?
~snipped
Another thing you may want to take in consideration is the Add wallet feature, the coins listed are in RadioBoxes, It may be better to use a ComboBox because overtime, more coins will be added and It won't be displayed in a good way.
Or maybe the user can type as well and if the cryptocurrency is available the app will show a suggestion while if not simply put a note that the currency isn't listed yet.