I don’t know about Novus and toothpaste. I have used a polishing stick and then future with good results. I’d definitively recommend you use future after polishing to get a smooth and clear part.
While I have the Novus system with the polish and different grades of sandpaper, I use also a multi grit sanding stick and then I polish it with some Permatex 403D plastic cleaner I have left over from my flightline days. It does a good job of cleaning and polishing canopys both full scale and subscale. If I have anything it won’t get out then it gets a future dip.
Future acts as a protector. Never a bad idea to use it when and where possible on canopies. One of its best attributes is, you can remove it after you screwed something applied over it.
I normally use a polising cloth system I picked up years ago. It starts with 3200 and ends with 12000 grit. Then a dip in future.
I have tried to future after the novus stuff, but the future would not adhere and it all had to be cleaned off later. I would say if you try it, make sure to wash ALL traces of the novus off. Also, future will not stick after using the novus plastic cleaner.