Exactly
And yet, remember Scarnhorst and Gneisenau. Although scarred, they made it.
BTW, about the time the GZ "would have been" ready it's roughly that era. Tirpitz was on the final too BTW, and it got unscratched to Norway.
Regarding the Murmansk line, remember that at summertime there is NO NIGHT!
Also bear in mind that the ship was (AFAIK) sailable. The speed was some 32 kts (?), and there was....Brest, - from 1940.
If you ponder on the Med, I wonder what the Brits could have done to stop her with full crew, - an independent air cover as well as escorts, passing through at Gibraltar. Well, I guess if she had existed properly, they would have had to take quite some measures for that possibility.
My conclusion is:
95% ready ship is a waste
100% was well possible if not for politics
100% would have called for British countermeasure worth much more than those odd 5%