The first iteration of Ethereum's Proof of Stake protocol, the standalone Beacon Chain, has been working since December 1st 2020: https://beaconcha.in/ https://

The first iteration of Ethereum's Proof of Stake protocol, the standalone Beacon Chain, has been working since December 1st 2020: https://beaconcha.in/ https://beaconcha.in/ So while not there yet, it's on its way to becoming proven technology. A big test will be how it handles general transaction processing. The Beacon Chain is limited to finalizing Ethereum PoW chain blocks at the moment.