I have used StandardNotes until recently. Unfortunately I had to change because I want to collaborate and share notes with my SO. If SN gets that I will probably move back as I already am using other proton services and I prefered using SN. I will continue to pay attention to your progress going forward!
Can’t you share an account? Or do you want it to be under your proton account?
Curious what you use right now for notes with your SO? Similar situation here and currently sharing a Notesnook login, which is less than optimal.
Do you use Joplin self hosted somehow with the collab? Or are you using Joplin’s sync?