Bip39 generator offline https://zenwriting.net/keenanctdp/how-to-create-a-bip39-seed-a-step-by-step-guide Regardless that it employs BIP32 technique you'll be able to even now import BIP39 seeds into Electrum wallet. Also besides BIp32 There may be BIP44 version which some wallet use for that era of seeds. Press X to abort passphrase application and maintain editing the passphrase. https://gogogobookmarks.com/story19997647/bip39-validate-mnemonic-a-secret-weapon-for-bip39-mnemonic-https-linktr-ee-bip39