Welcome!
Theres wide variety of aftermarket products you can get for your build:
Wooden deck from Nautilus Models
Photo Etch from Eduard, AMP, Modelbrass
Brass turned barrels from Schatton Modelbau
Brass screws from Raboesch
Figures from Warrior, Hecker & Gyros, Andrea
Flags AMP
Original kriegsmarine enamels from WEM
Rigging thread from Modellingtimbers
Decals Ulad, AMP
and so on...