This is great feedback. We are currently working on improvements on this specific finding. We'll continue to provide updates to make Firefox Lockbox a better experience. Thanks for trying and testing the app.
59 karma · joined July 10, 2018
You can find more about how sign-in and key management works in https://github.com/mozilla/fxa-auth-server/wiki/onepw-protoc...
The team is currently working on autofill from Lockbox into other apps: https://github.com/mozilla-lockbox/lockbox-ios/issues/486. This will only be available in iOS12 when that ships.
Are there other kinds of integration you see as valuable?
As you found, Firefox Accounts derives the encryption key from your username and password on the client-side; the server is never aware of your password. That encryption key protects your data on your device using AES-256-GCM, and is stored in its security enclave behind Touch ID or Face ID wherever possible.