Bitwarden.
My recommendation: Don’t use Vaultwarden (self hostable server side of bitwarden. Really easy to run and use). Why? You’re not a security personal, and securing your vault isn’t your job. You might do a slight mistake that’ll lead to the compromise of your vault.
The people at Bitwarden have their work dedicated to securing the vaults and all they do is security. And they’ll probably do it better then you. When it comes to serious matter, I prefer to trust the professionals.
I think you should explain how it differs from existing solution out there, like torrent and Syncthing.