Not that PoW and PoS are not themselves consensus algorithms but generally in PoS-using algorithms you just sign blocks, or "votes", etc with a private key that

Not that PoW and PoS are not themselves consensus algorithms but generally in PoS-using algorithms you just sign blocks, or "votes", etc with a private key that's been committed to with some amount of stake. In the case of Ethereum for example, a random number generator decides a set of stake that may produce the next block and when it's your turn you make a simple digital signature on place of where BTC miners brute-force a hash collision. In the case of Avalanche, nodes choose random stakers on their own and perform a repeated subsample across the staker set. Stakers respond with votes signed by a key thay was committed to when the staker first staked their coins.