Thought I might post my app here too.
I’ve released version 0.7 of YAFI, which adds support for modifying fan set points!
While they are only ‘on’ and ‘max’ set points, and not a proper fan curve, it is handled by the EC and does not require YAFI to run in the background. These set points also seem to survive a reboot.
YAFI supports both Linux and Windows, and you can download this release on GitHub or Flathub, or view my forum post here.