So, a SHA256 private key

What is a SHA256 private key?

A bitcoin private key is just a random number between 1 and 115792089237316195423570985008687907852837564279074904382605163141518161494336.

While the results of the SHA256 algorithm typically fall within that range, there is no need to use SHA256 when generating private keys. Any number

**chosen randomly enough** will work.

Does it means that I can use a bitcoin address on any coin using the SHA256 algo?

That depends on the signature algorithm that the altcoin is using and how the altcoin generates their addresses.

What about others algo?

If the coin uses a different algorithm for generating addresses, then their address won't be the same for the same private key.

I think I missed something.

I think you missed a LOT.

- You missed the fact that Bitcoin uses ECDSA key pairs.
- You missed the fact that the standard version 1 Bitcoin addresses requires hashing the public key with SHA256
- You missed the fact that the standard version 1 Bitcoin addresses requires hashing the SHA256 hash with RIPEMD160
- You missed the fact that the standard version 1 Bitcoin addresses requires a version byte in the front that tells the wallet what to do with the address.
- You missed the fact that the standard version 1 Bitcoin addresses requires the resulting value to be base58check encoded.