I did as you mentioned
1. It is showing BNB balance as ZERO, but I do have BNB balance. Attached screenshots
2. In attached screenshots when I click on TWT and search for DEUS, it shows message as NO ASSETS FOUND

Never mind my first answer. Let me explain this better
On trust wallet, you can use a particular chain to buy coin built on that chain, for example, you can buy TUSD which is built on ethereum blockchain with Ethereum.
So you can buy BEP2 tokens with BEP2 BNB
Which also means you can buy BSC tokens with BSC BNB.
You can convert BEP2 BNB to BSC BNB, but you can not convert any to ETH.
If you have BSC BNB, you will still not be able to convert to ETH to be able to buy ERC20 token.
The best you can do it to move you coins to ETH based exchanges to buy the coin you want to buy.