My answer would be that the Netherlands already had a very strong national identity forged in the late 16th and 17th centuries, so when Romantic nationalism became a thing in the 19th century it already had something to fall back on, quite unlike Germany which hadn't been nearly as succesful at forming one (not even in the 16th century, where proto-nationalism as an alternative to religious identity was widely attempted*). In the Netherlands there were already humanists intellectuals repurposing Julius Civilis' Batavian rebellion of the first century to provide a national epic centuries before the Germans did the same with with Arminius. And that's just on an 'intellectual'/artistic level. 19th century Romantic nationalism differed by being
popular too, but for that the Netherlands also had a long tradition of Orangism, which had always held widespread lower-class appeal.
There was simply very little need for anything resembling a new Völkisch approach to nationality in the Netherlands. There were already well-established traditions, including ones about Germanic antiquity, to fall back on, if the need ever arose for a story to stretch national unity. And of course, with the Netherlands being neutral throughout most of the 19th century, there was little need for a strident anti-Roman/French saga either, as was the case in Germany.
Consider that the Dutch 'patrior movement' in the latter decades of the 18th century came up with the whole 'Batavian myth': the idea that the Dutch had descended from the Germanic tribe of the Batavians, who had floated down the Rhine from "Germany proper" in hollowed-out tree trunks in some mythical past
The Batavian myth in some shape or form goes back much, much further than the 18th century patriot movement (all the way back to the Guelders Wars, last I checked), although I agree that the Patriots put their own spin on things. Mind, these are the same people that tried to repurpose the Dutch maiden into a Marianne analogue.
*Partially because the Dutch population was so well-educated and literate, the Dutch Republic managed to become one of the few countries on the continent where the politiques didn't lose out completely.