One of my grandfathers served on a German submarine, which must have been an intense and horrifying experience. The vessel he served on was actually sunk in the Atlantic by a British sloop. Thankfully he survived. I don't know how many members of the crew escaped the sinking uboat or how they did that, but survival was not the norm for the crews: Only 25% of all 40000 sailors, that served on German submarines during WW2, made it home.
If you want to get a lasting impression, of what serving on a German submarine during WW2 was like, I strongly recommend the movie "Das Boot", or better the full mini series of the same name which the movie is just a shorter cut of.
My other grandfather was as a radio operator. He must have served on the eastern front. At least later on, because he was captured by the Sowjet army. I recall only two things mentioned about him regarding his time during the war: He received some award or commendation for guiding surrounded troops to safety via radio messages.
The other thing I remember being told is, that after the war, when he had returned home from captivity, he would roll around and scream in his sleep.
One of my grandmothers worked in a small town's office since before the war and later during the war as a nurse in a military [?] hospital. When the nazis rose to power, the town got its own concentration camp. Not the big kind which is usually depicted in movies and documentaries, especially not one of the destruction camps. It was more like a makeshift prison in a building that looked like a barn. There were many of those smaller concentration camps all over Germany.
The nazis were popular in that town and after the takeover they put political opponents into said camp. Oddly the camp was in the midst of the town and the office my grandma worked in, was basically next to it. Everyday the prisioners were run and beaten through the streets to do forced labor outside the town. Basically everyone saw it, everyone knew it, but after the war most people denied it or kept silent about it.
Another thing she once told me, was about how she lost one of her friends. Her friend had given birth shortly before and hid with her child in a basement during an air raid. Unfortunately a bomb hit the building above and a fragment of the bomb ripped her head off. When they dug her out under the debris, her baby lay screaming next to her body.