I noticed a part that usually categorizes as a "Bricks Curved" but this special one categorizes as "Bricks Sloped". I would think it will be hard to find this part.
Slope Curved 6 x 1 with Black Vent Print (SW Republic Gunship)
42022pb02 • Bricks Sloped
I agree that minifigs sets that were normally ordered from the end of a catalog with something like 2 white astronauts and two walkie talkies should probably be supplemental. But I think a set that was sold in a box with 4-6 minifigs and sometinmes buit robots should probably not. But yeah, the line is not very clear. That's why I wondered if there was a clear definition of the supplemental tag.