If you already have an account on Ethereum, it can be imported into Binance Extension wallet easily, you only need to:
Export seed phrase
You can use Binance Extension wallet to control the same address on different blockchains, namely Ethereum and Binance Smart Chain.
You can pair your Binance.com account with your Ethereum address now. Read here for more details.
If you want to transfer ERC20 to its BEP20 equivalents, you can send them to Binance Bridge from the extension wallet directly. No need to interact with two different wallets.
You can use Binance Extension wallet to use those popular dApps.