Well, it was tech “built”, or at least the hull was. The german Navy was planning on war for 1944, not 39. They had plans for 100s more subs and at least a dozen more tirpitz/bismark class Battleships along with many more ships (destroyers, cruisers, etc). The Graff Zep was going to be the first. When war came it went on the back burner to the larger land war. The Germans for a short time tried to complete her after France fell, but when Hitler started eyeing Russia it got mothballed again.
Now the true WW2 geek question. Did Germany have any planes that could have flown on it w/o large modifications? I am not sure on the structual design of the BF 109, FW190, JU87 (did Germany have a torpedo plane?) Or were they designing other planes specificaly to be on a carrier?
Also, how big was this thing anyway. I read a book about the German Navy 20 years ago so my memmory is foggy. How to it match up to an essex class carrier?
Fun side note as far as this whole thing goes (learned it from WW2 mag). The japs and germs were exchanging tech secrets in 42 (from the few subs who were able to cross the globe and not get destroyed). The Germans had the blueprints to the Akagi (and the japs got rocket and jet tech in the exchange).