RETH* is one of the open source implementations of the Ethereum protocol. Around 2% of Ethereum nodes run it today.

Historically, there have been hundreds of blockchians that were basically slightly modified forks of Ethereum clients, operated by a small group of validators that sacrifice decetralization in order to achieve higher throughput. This seems to be a slightly higher effort verson of that.

*https://github.com/paradigmxyz/reth