Syncing data between devices / Backup data to server

[trymeouteh]

The ability to sync wallet data between multiple devices and the ability to have wallet data backup to a server to recover data in the event of losing all of your devices. Of course one should always have their seed phrases backed up but losing transaction notes, address book contacts, address labels, etc can cause issues especially when it comes tax time. I would like to purpose the following...

E2EE server with backing up

• Users can signup to a stack wallet server with their email
• All wallet data is stored on server but is E2EE
• Server is used to sync data between users devices
• Users can use official server from stack wallet or self host their own server
• Server code is fully open source
• User can login to server and download all lost data
• TOTP or 2FA

E2EE server without backup

• Users can signup to a stack wallet server with their email
• No wallet data is stored on server, just used to connect users devices to each other to sync data, similar to how Signal messenger works or Brave browser sync feature works.
• Server is used to sync data between users devices
• Users can use official server from stack wallet or self host their own server
• Server code is fully open source
• User CANNOT login to server and download all lost data since do data is stored on the server
• TOTP or 2FA

Integrate cloud storage providers into stack wallet

• Integrate cloud storage providers to sync and backup data
• All data is E2EE, nothing is store unencrypted in the cloud
• All code to sync between cloud storage providers are open source.
• Providers
  • Filen (E2EE privacy cloud storage provider)
  • Mega
  • Google Drive
  • OneDrive
  • Dropbox

File System Storage

• Will save wallet data to file system after every change and read file system for any changes coming from other devices
• All data is E2EE, nothing is store unencrypted in the file storage on the device
• Users can choose what to use to sync or backup their data such as Syncthing or a cloud storage provider of their choice
• File system read/write access could be hard on some devices, such as mobile devices due to OS limitations. Not even sure if this is possible on iOS.

I would prefer the first option or even having option one and two were users can choose if their data is stored on the server or just to use the server to sync data between devices. Perhaps stack wallet could run a server which will not store users data if stack wallet does not want to store this data but anyone can self host the same server and enable data storage.