My guess is that most of empty wallet buyers are buying them to sell the airdropped tokens (that not all people know of). Now when OP wants unlinked wallets, that makes me think that OP wants the private information specifically that these old wallets carry.... :/
In any case, nobody should sell their private keys etc., unless you know extremely well what you're doing. It's bad for security & privacy (for you and others) and generally not worth it at all.
You've gold plated the issue to much, check the US tax law specifically the IRS then you will know it's a legit (and urgent) need of buying such a wallet.