It is definitely possible to make an adapter that overlays crypto on top of any other storage drive - you could even make one yourself with a small computer like a Raspberry Pi.
However it would have to use an actual password, keyfile or smartcard instead of a fingerprint - the issue with fingerprints is that unlike any static data which could be passed on to a hashing function (or more specifically a key derivation function), a fingerprint scan is fuzzy and will always be slightly different, making the use of a hash impossible and forcing the crypto device to know the actual encryption key beforehand and only release it if the fingerprint matches.
If the device uses fingerprints then it would already have the decryption key in hand and an attack on it would be quite easy and would reveal the key.
Finally, have you tried using reputable software disk encryption solutions? On Windows you have VeraCrypt (one of the successors of TrueCrypt), on Linux you've got the former as well as LUKS. You can use those on any unencrypted storage drive.