Wonder if there is way to migrate Nostr profile to a new Private key. Like after some incident like Password manager hacks and similar as I guess this PK is not meant to be written on Paper - seems quite long random chars.
Discussion
Nip05 could be used for that to my understanding. Your profile gets tied to a domain and you can switch npubs (meaning nsec as well) that are associated. People would find your new npub from the lookup of the nostr address.
As for the paper, try Amber ... it is a vault for your nsec and you input your nsec into amber and other apps will ask it to siggn messages, so e.g. amethyst app, or other that supports amber, will not have the nsec directly. A nice thing is that you get your nsec in a 12 word format, bip39 basically, so you can have it offline. Amber is not on google play thugh, use fdroid to download it.