I could be wrong but the Lightning Network is hardly a proof of stake system, just used to open up state channels between two members for lots of off chain transactions before finalizing on the main chain.
Ethereum does not use Proof of Stake, it is a proposed change that is being worked on, with a timeline of several years before it will be put into action, and that's only if the network accepts it.
I can't tell if this is a joke or not but i'll bite. Delegated proof of stake is exactly as you describe and there are 10+ $1B chains that have this mechanism.
It's not. It still uses proof of work, for now at least. They say they want to implement proof of stake. THAT will be interesting, but I want to see if they ever get there.
Proof of stake is a decentralized consensus mechanism that is (usually) trustless, and prevents attacks like double spending.
Most notably, Solana, Cardano, Polkadot, Avalanche, Terra, Algorand, Polygon, Elrond, and Fantom are all using permissionless networks where nodes which have some amount of the native token of those blockchains staked produce blocks and validate transactions
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