If you aren’t already you need to be a Theme Approved partner you can find information on how to apply for that Here The theme and wallpaper seller is a closed ecosystem.
Information on how to apply to be a theme partner can be found HERE
To sell a Theme App (Theme, Wallpaper, Icon and AOD) requires you to register for commercial seller status.
Sellers don’t need to be Samsung’s partner and should not sign for partner type seller office account.
I hope this helps if you have other questions feel free to ask.
Ron
Samsung Developer Program