The most important thing you have not mentioned is redundancy.

One back up is no back up at all. You need, at a minimum, two back ups, with one of those being stored off site. Writing your seed phrase on paper and storing it in the same building (almost always your home) as your hardware wallet is effectively no back up at all, since you will lose both hardware wallet and seed phrase back up with any natural disaster, fire, flood, etc. You should have your seed phrase written on two separate pieces of paper, with one of those stored in a secure location away from home, with a friend or relative, in a safe deposit box, etc. If you are uneasy with a copy of your raw seed phrase being stored away from home, then use additional security such as a passphrase or multi-sig, although these also require at least two more separate back ups.

That way it doesn't matter if your home is destroyed and you lose both your hardware wallet and your seed phrase; you can always recover from your second back up.