Valdemar II,
Nice to see you've back off your "Royal Navy To The Rescue" claims. Let's refute your other idealistic ideas now...
Denmark produced food to around 5 million people in 1914...
And did so due to a reliance on imported nitrates. Even with the Haber-Bosch process, occupied lands, and foreign laborers Germany still couldn't manage pre-1914 agricultural yields. Zealand isn't going to be receiving shiploads of fossilized bird shit from Chile. Agricultural yields will drop and "free" Denmark will starve. In the OTL starvation happened to a much better positioned and technologically advanced Germany, a poorer, besieged, less advanced, and geographically constrained Denmark won't be able to do any better.
... beside that Denmark can still import food through Sweden...
Only if the Germans allow it. There's strategic purchasing for one thing, Germany can simply buy up Sweden's ag surpluses. There's economic pressure for another. Finally Germany can lay mines or operate light craft
... which at the very least can import that through Norwegian harbours. Germany can't close Kattegat down without declaring war on Norway.
They can do the next best thing and that will be enough. Norwegian freighters creeping through Norwegian and Swedish waters will still need to enter Danish waters to deliver food and goods to Denmark. When they do, they're fair targets for Germany under the same blockade rules Britain is enforcing in the North Sea.
The reason that convoys to the Baltic was impossible in OTL...
Sorry, but no.
Convoys to the Baltic weren't impossible in the OTL, the RN and USN routinely covered
Scandinavian convoys with portions of the Grand Fleet. What was impossible in the OTL were convoys to
Russia because those convoys had to pass German occupied lands in a narrow sea.
The Germans occupying Jutland aren't going to let convoys headed for a besieged Zealand pass unmolested anymore than they let convoys heading for Russia pass unmolested in the OTL. And the Grand Fleet isn't going to be able to force convoys through the Skageratt and Kattegat any more than they were able in the OTL.
I know you've most likely got some emotional attachment to the idea of a rump Denmark becoming another "Brave Little Belgium", but the geography is stacked too greatly against that occurring. We need to be realistic here. Zealand is going to starve and be forced to surrender just as with Serbia.
By the way, care to explain how a besieged Zealand is going to produce all the munitions, mines, ships, and other materials your defense scheme will require? I noticed you forgot to answer that one last time I asked it.
Bill