Is there some method of digging holes that I am not aware of that doesn't make it obvious there is a freshly dug hole?

I mean, that spot in your neighbors yard that looks freshly dug would probably be a good place to look. (They were occupying the whole country)

If you want a digging to go unnoticed, you don't try to conceal the digging; you dig in a place where lots of other mundane diggings are already happening.

So, not going out in the middle of the night in ninja swit; but chearful gardening in the Church's front yard instead.

You can even put a heavy, thorny bush on top, so people will be too lazy to undig it by accident.

I had missed the point about Nazis already going parading on the street. In that case, indoors methods of dealing with the medals provide a big advantage.

I'd probably have tried to melt them, though.

I believe a there is a plot line in Pulp Fiction that touches on a solution satisfying both constraints.

The Nobel Prize medal appears to be about 2.5 inches wide, which would make it immensely unsatisfying in at least one constraint.

You'd need to start with smaller medal first.

If he had hidden it, and it was never recovered, then it would be like a really cool 'Copenhagen mystery' - the 'lost Nobel Prize'.

They could have a little festival every year to look for it ...