This idea has been floated. Scammer Richard Heart is trying to this with Pulsechain, and somewhat more seriously, Avalanche wanted to run such a forked Ethereum as a subchain, but this appears to have been abandoned.

It is an interesting scenario to think through, in particular what happens with stablecoins etc. which would not be redeemable.

Ultimately, I predict such efforts to fail badly. The fact that e.g. Ethereum NFTs are copied will in fact work against such a fork getting traction.