As avernite said the problem will probably be resolved by cutting off the germans on the dutch islands and then the soldiers will happily surrender without you having to directly attack them.
OTL The Germans on the British Channel Islands were completely isolated by Autumn 1944
and yet they never surrendered ... or even offered to do so.
Instead the German Foreign Ministry suggested that the British could evacuate the women, children and old folk
which would of course leaving the occupiers in place along with all the men as hostages and forced labor
(and
incidentally an improved food situation for defence).
The Island commandant refused even to discuss terms when approached directly.
Only in December 44 when the garrison itself was lacking food did they agree to Red Cross ships to feed the civilians
(which left more of the local sourced food for the occupiers of course)
Similar stories happened in Holland during the winter of 44-45.
The Nazis in both Holland and the Channel Islands only surrendered after the fall of Berlin and the signing of a formal capitulation.
So I doubt that even in ATL anything will come of offering the isolated garrisons of these islands a chance to give in without a national surrender.