especially in the context of foodstuffs the decagramm (or just deka in common language) is getting used in Austria, don't know if it's the same in germany, so it would be a 25 deka burger

Eh that's regional still, like in dutch we've changed the meaning of old imperial words to be equal to metric quantities, though probably used more common by older people. So 1 ons (ounce) = 100g and a pond (pound) is half a kg. But this is mostly used at a butcher. For other stuff we mostly just use the metric nomenclature.

And these signs could have used ounces instead. But they didn't. We had other units available. The units weren't the issue