Hi, You probably want to use X11_TYPE=modular (after cleaning and deleting packages) to get pkgsrc Xorg. Then, run the startx you get from pkgsrc.
We have some old versions of drivers but I see that the check to using the new ones is for NetBSD==7. It should be extended to ==8 (NetBSD 6 did not have a new enough DRM), assuming you use the meta-pkg. We don't have xf86-input-synaptic in pkgsrc, it must not be hard to add, but I'm not sure how Xorg works too much (I don't know how to tell which input driver I am using). Could raise it as an xsrc bug.