Although they should be based on compressed keys only, there where cases like these:
I have a Nano S wallet initialized by restoring my BIP39 mnemonic, segwit path, no passwords.
This BIP39 should be, in principle, a BIP32 hierarchical deterministic wallet, and produce as such only compressed public keys.
However, in my case they are uncompressed. When I call the getFirmwareVersion() method, it responds that 'compressedKeys': False and when I call getWalletPublicKey() I obtain, indeed, public keys in uncompressed form (\x04+x_coord+y_coord)
Source:
https://www.reddit.com/r/ledgerwallet/comments/7znmwr/nanos_keys_are_uncompressed/So it does seem there are historical cases out there with uncompressed keys based on BIP32/39.