Is it possible to use an ERC token contract on the Binance chain? Would you just replace the uniswap router for the pancakeswap router? Or is it more complicated than that?
ERC20 and BEP20 are not fully interchangeable. BEP20 has some extra stuff, if I remember right, so you'll need to add those.
Also, a token typically has no idea about DEX routers - that logic should be in another contract which simply utilizes the token. Token code should be kept very minimal and simple.
If you take a look at binance docs, they use the exact same functions as ERC-20 openzeppelin packages do (https://docs.binance.org/smart-chain/developer/issue-BEP20.html). Also, almost all tutorials use openzeppelin erc-20 packages to issue BEP-20. Thus the only difference between erc-20 and ‘bep-20’ are the chains the smart contract is hosted on. You can basically deploy the exact same erc-20 contract on both ethereum chain and bsc.