Try Turtl (https://turtlapp.com). Disclosure: I built it. It's actually end-to-end encrypted (ie, don't lose your password) and has collaboration features. I've mentioned elsewhere in this post that the conflict resolution is terrible, and also I haven't done a release in quite some time, but I'm (slowly) working on an updated version at the moment (hopefully with better conflict resolution).
> Our app, Supernotes, is not E2EE
That should have been at the top, and saved me two minutes.
If someone develops a usable, cross platform, e2ee notes app with collab/sharing features, I'll gladly pay good money to use it.