I had an idea for this you might want to consider adding: store the passwords/keys in the client, no server… but then shamir’s secret sharing to shard them along your contacts.
So when you open the app it asks you to choose five (?) friends you trust (who don’t know each other) from your contacts and it’ll ask them to install the app to help you store your secrets.
Then if you ever lose your phone or whatever when you reinstall the app you just have to remember at least three (?) of the five people you trusted and then will be able to restore your keys!
It would also ping the other contacts when open to make sure they still have your shards and redistribute them as you add/change/delete them.
So when you open the app it asks you to choose five (?) friends you trust (who don’t know each other) from your contacts and it’ll ask them to install the app to help you store your secrets.
Then if you ever lose your phone or whatever when you reinstall the app you just have to remember at least three (?) of the five people you trusted and then will be able to restore your keys!
It would also ping the other contacts when open to make sure they still have your shards and redistribute them as you add/change/delete them.