Binance does not support borrowing BNB on its platform; on-chain platforms support it, such as Venus and Alpaca, but many altcoins do not support collateral, so it may not be possible to directly collateralize and borrow $BNB.

The general recommended path is: collateralize altcoins on Binance, borrow USDT/USDC, and then go on-chain to collateralize USDT/USDC to borrow BNB.