> Visual or terminal-based means to configure rudimentary touchpad settings. The fewest options I could imagine supporting for v1 would be: scroll speed/acceleration, scroll speed, natural scrolling toggle, hopefully support for gestures.

You gave up on libinput after an inability to configure scroll speed, but the rest of those are all configurable with libinput and libinput-gestures[1].

I don't use gestures yet and default scroll speed has always been fine, and the following tiny libinput configuration hits the rest of your points.

  $ cat /etc/X11/xorg.conf.d/30-touchpad.conf

  Section "InputClass"
      Identifier "touchpad"
      Driver "libinput"
      MatchIsTouchpad "on"
      Option "Tapping" "on"
      Option "TappingButtonMap" "lrm"
      Option "NaturalScrolling" "true"
  EndSection

Is there a reason you haven't asked the libinput maintainer about whether configurable scroll speed would be welcome upstream (in the prior post, it comes across like your question was far more open ended)? Forking it just to add scroll speed configuration and replicate work that's already been done elsewhere seems a little excessive.

[1] https://github.com/bulletmark/libinput-gestures