Swan would only see the new xpub’s addresses. Do you mean you generated a new seed phrase on an existing hardware wallet? My understanding is they wouldn’t know your ownership of any addresses linked to a different seed phrase. But your Swan purchases would be sent to your new wallet and those would be visible to Swan (and any future bad actor).
Discussion
I created a new wallet within my hardware wallet. No new seed phrase but its UTXOs are separate from the rest I think. Well when I generate an address to receive it’s for that individual wallet.
Hmm. I always assumed you could either have a single xpub per seed phrase, or have multiple “wallets” by adding a passphrase to a seed - which I believe generates a new xpub. But this may be a bit beyond my technical know-how, at this point.
To your original question, the reasons not to give your xpub to swan include the privacy concerns I mentioned. If you move those utxos out of cold storage later (or just move to a different wallet), you can gain forward-looking privacy via coinjoin but Swan/onlookers would know you moved those coins.
I understand. Thanks for the info I appreciate it.