German WW2 12GA HE projectile

I was told long ago that in the last days of WW2 there was a 12GA HE projectile developed and supposedly made.
Issue was for the so called “Volkssturm” (something like a civilian defence force consisting of youngsters and elderlies).
The projectiles were supposed to be given to people who owned 12GA shotguns and regular cartridges were to be “cut open” on the top (shot removed) and the projectiles being inserted.
I am not sure about the anecdotal part of how it was to be used but such a projectile was developed as per some doc which mentioned it.

Anybody with better info on all this?
Do real specimen exist?
Are documents available?

Alex, I don’t know if the whole story is true, but this explosive shell for shotgun did existed. I think there are drawings of the projectile and fuze; I’ll check later.

Fede, I think I saw one when I was very young but back then (like 27-28 years ago) had no real interest in it. So it can well be that they were also made.
Actually this was the reason for my initial posting.

Here they are (from M. Heidler article in Small Arms Review).