More parallelizable execution environments can run on top of the EVM. That's what Fuel is building with its Ethereum-based Optimistic Rollup, with a goal of eventually making the UTXO model Turing Complete (Fuel v2.0):

https://docs.fuel.sh/v1.1.0/Future%20Roadmap/Planned%20Featu...

Solidity is only the language of the C-Chain, which is basically the EVM with better scalability but only constitutes one part of the ecosystem.

It is currently the most visible part because most of the protocol's features are still under development.

But the Avalanche protocol itself isn't tied to the EVM or Solidity, it is designed to let you run any customized blockchain.