There is an open feature request for an interface to create custom acceleration profiles: 464868 – Create UI to generate and use a custom Libinput acceleration profile - this looks like something that will just require someone with the time, ability and interest to jump in and figure out how to implement 
The following post was helpful to me for context on why libinput itself doesn’t describe a configuration interface: How to access libinput properties in Wayland for an external touchpad? - #2 by jpetso