Android nestedScrollView - how to make it horizontal?

No

I do not believe NestedScrollView can be scrolled horizontally. According to docs:

For vertical scrolling, consider NestedScrollView instead of scroll view which offers greater user interface flexibility and support for the material design scrolling patterns.

As per the text in bold, I believe NestedScrollViews were only made to scroll vertically.

While NestedScrollViews are "just like ScrollView" (link), the docs do also state that:

Scroll view supports vertical scrolling only. For horizontal scrolling, use HorizontalScrollView instead.

(Both blockquotes come from here)