you don't need to be vaxxed for HiveFest or visiting NL, depending on your origin of entry. If within Schengen, no problems at all. You could travel through a more laxed schengen country for entry if you are from outside of schengen. Or if you have had covid in past 180 days you can also enter. Plus I don't think they really check.

At least in NL there is nothing, no health pass, no QR, fortunately.

Here is an article about all this on the HiveFest FAQ:
https://hivefest.freshdesk.com/support/solutions/articles/80001029295-covid-qr-health-pass-vaxx-mask-in-netherlands-tl-dr-no-requirements-