I've read quite a few memoirs of front line soldiers from both sides. To a man, they all we're fighting for the guy next to them, not politics. They all complained about the conditions and they all just wanted to get home.
Almost every German memoir includes accounts of being treated as Liberators by Russians. Some were involved with taking time to bury church bells and the like during the retreat to be recovered by the villagers at a later date.
Most believed they were fighting for Europe against Russia. Quite a few were also told in POW camps that they would soon be fighting with the Americans against Stalin. I believe Otto Carius thought he was to help train tankers and was upset that it never happened.
It must be difficult as a Country to come to terms with a past that is so recent, but you have an invaluable source in your Grossvater, it's important for him and you that talk about it.
My mother in law's father came from a family of five brothers. He was killed in Brest as a US infantryman. She visited one uncle in New Jersey as a POW. Another uncle died in a camp as a political prisoner. The others served in the Wehrmacht.
I for one would love to hear what the conditions were in a Tiger, bits of info technical manuals can't give: the feel, sounds and smells of sitting inside one of those beasts.
Some books eluded to this, Otto Carius frost bite from falling asleep against the turret wall, another using the muzzle-break cover as a latrine, tankers washing their clothes in gasoline and so forth.
Any info like this would be a pure gem, please feel free to post or email.