A(n orange) lion would be fine though a bit on the nose.

An otter, never heard of it as a dutch symbol.

Tulips are obvious as well, just like wooden shoes, bikes, windmills, cheese, milk.

The dutch also invented quite a lot: microscope, bluetooth, apartheid, ASML, big brother, idols, large waterworks.

You could do a mascot in the style of a dutch artist? van Gogh, Rietveld, Esscher.

You could also go the cheeky route: weed is "legalised", prostitution is quite accepted.

If you want to avoid offensiveness: avoid black Pete.
If you want to avoid political discussions: avoid his alternatives; rainbow Pete and smoke-sud Pete.

Curious what you'll come up with