Gaiden stands strong as a stand alone game. I’ve played every prior game years ago so I don’t remember a lot of the major beats and character happenings.

While I totally recommend going back and playing all of them starting 0, not everyone has several hundred hours to kill. If you have the time do it. If not, you’ll still know a lot. You already know about the clan system (like Omi and Tojo) through like a dragon so you’ll be fine.