I have SmartChain BNB in my Trustwallet (TW) account.
1. Is it possible to buy ETH-based crypto on TW with SmartChain BNB. If yes, then please inform me how.
2. As I am a newbie, I want to buy ETH-based crypto for only $5.1 amount. Will it be cost-effective, as many people are saying cost will be high on ETH transactions? So I don't end up with like paying $5.1 for buying and paying $2 or $3 for transaction fees.
If you buy using BNB of course you can, but what you get is WETH (ETH in the BSC network) not the original ETH of the Ethereum network, because it is true that the Ethereum network has very expensive transaction fees at this time.
If you are interested in buying WETH you can enter the trustwallet dapp and select pancakeswap
Go to the market section, you will find where these tokens are traded.
https://coinmarketcap.com/currencies/deus-finance-2/markets/