You may buy crypto on Bake directly with Fiat.
To do so, please click on the "BUY CRYPTO" button on the top right of your Bake page. Then this pop-up window should appear:
Under "I want to buy" you can choose DFI, BTC, ETH and SOL. Please note, depending on the payment service you select, there might be different cryptocurrencies shown and different procedures / requirements for the purchase.