@merclyn, that one wont work in this case because it's different derivation paths so it's different public keys from the seed.
Your right, I should have understood the OP's main issue before I posted.
What I thought I was responding to was this scenario:
A Ledger Nano S was setup new with segwit addresses, but it provides a xpub in the log.
According to SLIP-0132 (
https://github.com/satoshilabs/slips/blob/master/slip-0132.md) there should be different version byte (or different prefix on that key)
The ledger I tested should have produced a key that started with ypub (P2WPKH in P2SH), but it produced an xpub key.
The Trezor I tested displays the correct extended public key for the address scheme used..
The site I posted earlier would change the Bytes and return a ypub (or zpub if needed).
Thanks for the correction.