can you use aws kms to store ethereum/solana keys? did anyone see it in prod?

Yes, it’s possible to store Ethereum or Solana private keys using AWS KMS, but not directly. This is usually done through custom integration.
n also the key formats used by Ethereum (secp256k1) and Solana (ed25519) are not natively supported by AWS KMS.

whatever, some companies successfully use it in production by implementing custom code and external libraries.
coinbase uses a mix of CloudHSM also metamask supports AWS KMS integration for enterprise key storage.