I doubt there are any services which can offer what you need, but most services/business which accept BTC usually also accept Fiat. Even if such services exist, i'm sure the fee is big, so i think it's better to ask services/business if they also accept Fiat.
I think he may asks the options like payment API done by bitpay and etc... In that too without wallet option is not available at all. If you expects any merchant in-between the any transaction. Then bitcoin also use to be like banks.
Most attracted thing about bitcoin is a anonymous feature and p2p transaction without intermediation but as you asked anything comes that is bad for bitcoin and altcoins community.