Trying to buy Binance Coin on Pancake Swap, but need Binance Coin to buy it. How can I buy it my first BNB?

I don't have a Binance account. I was intending to make a trade on a DEX binance network (Pancake Swap), but I have USDC transferred in from Ethereum. I've never owned BNB before, but it seems that I can't even buy BNB without BNB, making it impossible to purchase anything. How do I get around this? I didn't have this problem when transferred USDC to Avalanche Chain and then using that USDC to buy AVAX. It asked for USDC as a fee (via Trader Joe).