I'd like to add my support for this feature, especially as I use GoodNotes for both personal and professional work. At the moment, I am much more likely to use other apps for personal or sensitive work and have to move between programs. For me, it would be most useful to be able to password protect (or better yet, 2FA protect) specific notebooks, but it would be acceptable to simply protect the whole app.
I'd like to add my support for this feature, especially as I use GoodNotes for both personal and professional work. At the moment, I am much more likely to use other apps for personal or sensitive work and have to move between programs. For me, it would be most useful to be able to password protect (or better yet, 2FA protect) specific notebooks, but it would be acceptable to simply protect the whole app.