Discussion
I figured out why I can't control my touchpad in #NetBSD.
The reason: It's an Elantech touchpad that is not recognized as Synaptics, which is the brand of touchpad that has all the levers in `sysctl`
And just as there is no `sysctl hw.synaptics`, there is also no `sysctl hw. elantech` available.
And as you can see in the man page, there are only two tweakable parameters for elantech, and I can't even access those.
I found out for sure by booting the NetBSD kernel with the -x switch, which told me that my touchpad was NOT synaptics.
Then I booted into Debian and found out from its dmesg that I have an Elantech touchpad.
So it's kind of the end of the line for this laptop and NetBSD. I never got far enough with #OpenBSD to see if I can stop touchpad tapping (which I was able to do on my now-dead 2017 HP Envy) ... and I wonder how #FreeBSD will treat it.
@passthejoe Probably because it's one of the newer elantech revisions which the driver doesn't know about yet. I heard there's a dev with one, but we also need to keep the older code working...