Our Dutch ancestors rarely had a last will drawn up. Most were too poor to have any goods to leave behind. But even people who did own property often did not feel the need to have a last will, since they were happy with the default arrangement under the law.
The wills that do exist can be found in notarial records (in areas and periods where notaries were available) or voluntary court records.
Bij het archief van Dordrecht staan op Internet weeskamer uitsluitingen waarin summier wordt vermeld wie de zorg op de kinderen zal nemen.
I have several ancestors who left wills, though I have a hard time understanding them. And some of the writing styles! Oh my gosh!