9 years later i'm having the exact same problem as you..... have you found anything yet? i'm desperately searching for dutch hard rock lol

Misschien kan je Van Dik Hout of De Heideroosjes eens proberen? Maybe you can try Van Dik Hout or De Heideroosjes?

I'm learning dutch as well, I like the folk metal band Heidevolk and their single "een nieuw begin" it's my favorite dutch song right now. https://www.youtube.com/watch?v=ptN7OI2TRDo

De Kik maybe? Its more like the beatles...

They're not from Holland but from Belgium but they sing in Dutch: Noordkaap, and Monza. It's more alternative pop/rock than metal though. These bands also sing in Dutch: The Scene, Acda en de Munnik, De Trockener Kecks (there's a double point accent missing on the o, sorry I can't find it on my keyboard) De Dijk, Doe Maar, Grof Geschut, De Poema's, Spinvis, VanKatoen (<- I think you might like this band. It used to be Van Katoen, maybe you can find both on Youtube, not sure) Good luck!