Fundamental principle of owning your own crypto is centered on recovery seed. Many people wrongly think hardware device itself is most important thing but it is not. Recovery seed which is list of words you write down is master key to all your money and is what essentially acts as your actual wallet. Physical hardware wallet is just secure lock or tool that manages this key and makes sure it never touches internet. You are required to write seed down because it is single piece of information that proves you are owner of your funds. Crucially because all major wallets follow an open and shared language standard your seed phrase will work to restore your money on any other brand of hardware or software wallet. This setup guarantees that your money is safe from hackers and that you can not lose access to it even if company that made your original device shuts down. This absolute control over your key makes you true non custodial owner of your assets.