Can Eth 2.0 be built on a sidechain?

Could Eth 2.0 be built on a sidechain that's better than ethereum 1.0, like deploy erc20 token on another chain, add bridges and get the benefit of multi-chain?

Pardon for my ignorance, but is it correct that eth 2.0 has not been deployed yet? There is still time for eth 2.0 to be built on a more efficient L1 chain?