Support for Notebook/Category as a folder
Currently if in Nextcloud Notes app you would create a note and assign a category to it, then this note would be stored in Notes -> [Category_Name] -> Actual_Note.txt path, this is currently not supported by GNOME Notes/Bijiben. But GNOME Notes/Bijiben supports notebooks, which seems to work in a similar way - notes are organized into notebooks, much like in Nextcloud where notes are organized in categories - seems like the same thing just with a different name.
In other words, GNOME Notes/Bijiben should be able to read notes from a subfolder. Subfolder name would be used as a notebook name, and the notes in the subfolder would be inside that notebook.
I would be willing to implement this myself with some mentoring/guidance.