CMIIW.
I did tried to use that wallet and when I'm swapping a BSC token, it is requiring me the BNB-smart chain. And that would probably be the same with Ethereum for ERC20 and TRX for TRC20 tokens.
All BEP20 tokens will require BNB-smart chain token to pay the fee without it transaction will get cancelled. Trust wallet is multi-cryptocurrency wallet, which means you can use it store almost all kind of cryptocurrency.
For ERC20 tokens you need gas (ether) to complete any transaction. For TRC20 tokens you need Tron.
Without it the transaction won't proceed instead, being cancelled means that the transaction has been processed then cancelled.
Yes, that's it, you've verified what I've said about other coins that needed their respective coins/tokens for the gas fee.