Note that for Ed25519, all components must be hardened.
This is because non-hardened [PK] derivation would not work due to Ed25519's lack of a key homomorphism.
Specifically, you cannot derive the PK associated with derivation path a/b/c given the PK of a/b.
This is because the PK in Ed25519 is, more or less, computed as 𝑔𝐻(𝑠𝑘),
with the hash function breaking the homomorphism.
Aptos derive path is 637
Parse and validate a path that is compliant to SLIP-0010 and BIP-44 in form m/44'/637'/{account_index}'/{change_index}'/{address_index}'. See SLIP-0010 https://github.com/satoshilabs/slips/blob/master/slip-0044.md See BIP-44 https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki
Note that for Ed25519, all components must be hardened. This is because non-hardened [PK] derivation would not work due to Ed25519's lack of a key homomorphism. Specifically, you cannot derive the PK associated with derivation path a/b/c given the PK of a/b. This is because the PK in Ed25519 is, more or less, computed as 𝑔𝐻(𝑠𝑘), with the hash function breaking the homomorphism.