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Since it would be an optional feature to use. Lets call it advanced. If you would actually go the route of duplicating accounts, which i dont see necessary, this option would probably be utilized by maybe a couple thousand accounts in a year.

Feature addition could be on request.

The more I think about it, I don't see why a hardware wallet wouldn't be a big problem solver here. It's one of the best forms of 2fa we available. If we got on Ledger/Trezor someone could secure their account very cheap and most in crypto already have these wallets.