If I want to share a note with a guest to seek their feedback, but I don't want them to be able to change the actual content in the note, there is currently no way to do this.
It would be great to have a comment setting for guests to view/add comments that is independent of their view/edit access. Another way to do this could be to add a workspace setting in the document access section that determines whether guests can comment.
You can now allow guests to add in-line comments on documents! In the Share menu > Guest tab, you can control permissions for whether guests should be able to view only, view and comment, or edit your document. The Shared icon will appear next to comments added by guests.