I'm a (non-Dutch) Calvinist, so I'll take a crack at it.
Calvinist theology and religious culture is very socially conservative, and very fiscally conservative/pro-business, even by conservative Protestant standards. A Dutch Calvinist is more likely to observe the Sabbath (e.g. not go to a restaurant after church), view divorce harshly, and adhere to free market economics than say, an Scotch-Irish Baptist.
As Hofoid said, the Dutch Reformed have built a strong support structure outside of the state, similar to Mormonism. This probably leads Dutch Calvinists to be less supportive of the welfare state than other groups. These factors make Dutch Calvinists tailor-made for the pre-Trump GOP. It's less of a great fit in the Trump presidency, but the attraction is still there.
Lastly, the Dutch were an historically GOP voting group, so there probably are some ancestral GOP votes that you wouldn't get with say, similarly situated Latinos.
This is basically the case. Interestingly, Dutch-heavy counties in NW Iowa, SW Minnesota, and SE South Dakota seemed to swing to the GOP in 2016 whereas the heavily Dutch counties in Michigan (Kent and Ottawa) swung the other way, though this is almost certainly attributable to the educated suburban vs. rural divide in terms of swings.
In this sense there probably is a divide among Dutch Calvinists, with the more rural ones being solidly GOP/pro-Trump (as evidenced by Steve King continuing to win Republican primaries in NW Iowa, which is very highly Dutch Calvinist) while the suburban ones, while mostly still Republican, are much more Trump-skeptical - basically, Steve King vs. Bill Huizenga is the dynamic here. That being said, I think both groups will remain very Republican in the years to come.
