Breek sdk powers many bitcoin wallets. They are rolling out a way to store seed phares that is identical to how we already storing nostr keys at
They use a client-side passkeys flow so that you don't have to remember your seed, although you may export it at anytime.
However, we went a step further to make sure we can never steal your keys even if we wanted to. The vault (login module) is on a separate domain we don't control. By default it is on Github Pages. You may point to your own fork there or to your self hosted version anywhere by changing the url on the settings page!
You can read the breez blog post here: https://blog.breez.technology/no-seed-no-sweat-introducing-passkey-login-for-the-breez-sdk-2cb7a7ee0279
And check out or fork our vault source code here: 
44billion
One login, many apps
GitHub
GitHub - 44Billion/44b-vault: Your Nostr keys safe
Your Nostr keys safe. Contribute to 44Billion/44b-vault development by creating an account on GitHub.