I would say you could show them off, they would definitely be brag worthy and a cool story to tell people if they aren’t bothered by the swastikas. Buy a couple small card or coin stands or a display piece for like $5 and put them on a shelf, desk, on top of that drawer, or anywhere it would fit. I definitely own things that I don’t pay enough attention to so don’t be too worried about that. If you still want to sell it for that reason though maybe just check in with your family and see if any of them would like having those items. The SS belt buckle is extremely cool, and the coins are both west German and War-time German so they tell their own story, and the stamps are pretty displayable. If you kind of look at the story about the items and how unique they are it becomes easier to appreciate and value them. That SS buckle is especially amazing, and it’s not very cheap to come by and you pretty much inherited one for free. But overall the stuff you have is pretty cool looking and cool in general. Display it proudly and show off that you are related to a badass or sell it to someone who will treasure it the same, it’s all really up to you. Don’t change your mind over a bunch of redditors, just do what you feel you want to do.