The Woodturners Finish (by General Finishes / Exoticblanks) I use is not a friction polish. It is a water based finish.
As a water based finish, it will raise grain on most wood with the first coat or two (unless the wood is sealed first). The raised grain will have to be lightly sanded. You wouldn't want to have your decal applied to raw wood and have to deal with sanding the raised grain.
Woodturners Finish is great on wood, especially in cases where you don't want the darkening that can come with an oil finish. I would not use it on resin (aka "plastic"). For me, that means I wouldn't use it over a decal either.
But, if I were going to use it over a decal, I would apply it with a spray gun.
Ed