It’s not that big of a deal ! For French, for instance, there are about 20 different layouts available. But they’re all AZERTY. They are mostly minor regional variations, and slightly different takes on the special keys, like the one you want. The core of those layouts is all the same.
All you need is a variant german layout that differs from the one you’re using only on that key and maybe a few other odd ones like that. I’ll take a look.