pin Some of the things you have are default when not specified, so you don't really need them on a native NetBSD system.
Would have bet so; coming from an illumos/macOS background (I started using pkgsrc before coming to NetBSD), where most of those settings (all?) aren't taken for granted, I embraced the habit of always specifying them so as not to get confused, even though nowadays I don't use neither macOS nor Illumos (but I do use pkgsrc on Linux).
Off-topic note / advocacy moment: for the record I've also used pkgsrc on DragonFly at the time when it was its official package management system, on Solaris 10 with SunStudio 12.1 compiler and kind of got it working (just to compile tcsh) on IRIX with MIPSPro compiler....because pkgsrc is that good.
Unfortunately my last Illumos installation, a Samsung laptop, died few months ago (bad blocks on HDD, unreadable sectors, multiple failures, not gonna waste waste money in such a old machine) and there's no newer hardware where to put it for desktop usage. I miss Solaris, but in the meantime I'm enjoying Linux
Fun fact: On both Solaris and IRIX, as well as Illumos up untill very recently, you would also specify ABI={32,64} inside mk.conf, as userland by default is multilib and consists of both 32bit and 64bit ELFs, with a 64bit kernel (somewhat like nowadays it happens on Windows NT 64bit, where you also have 'Program Files(x86)')
