The founder of the hardware wallet knows nothing about your wallet seed phrase.
We assume that this is a fact, although we can never claim it with 100% certainty, especially not for those hardware wallets that are not completely open source.
Every hardware wallet is vulnerable to physical attack but Ledger wallet claim they have the needed highest level of security to withstand both physical and software attacks and it will be nice if we can see someone from the crypto community to confirm if this actually true.
As far as I know there is currently no physical attack that could be successfully performed on Ledger (S, X, S Plus) although they have existed in the past - but that doesn't mean that there isn't one that hasn't been made public, or that there isn't one which has not yet been discovered. Trezor, on the other hand, has a vulnerability that cannot be repaired with a firmware upgrade, and the seed can be extracted relatively easily and cheaply if someone comes into possession of your hardware wallet, and you have not protected it with a passphrase.
Meanwhile to prevent a physical attack is better to encrypt the wallet
The only additional security that the user can additionally set is the passphrase mentioned above, and there is no other way (that I know of) to encrypt the hardware wallet. The only thing you can do is store it safely away from the reach of anyone with bad intentions.