Any suggestions for an architecture to reach to Bitcoin's wallet structure for Ethereum?
My suggestion is don't. Ethereum is not a UTXO blockhain, but an account-based one. Any Bitcoin like wallet structure on Ethereum is not practical, or not needed.
For creating a hot wallet please see this answer.
You do not need geth to create a wallet. Ethereum account is just a private key that is a large 256-bit random integer. Then this private key can be imported to any wallet software or your own program.