There are lots of "Pioneers" and more are cropping up all the time. Anytime someone blazes a new path of study or inquiry, they're a "Pioneer." There are "Pioneers" in Western Martial Arts, RBSD, HEMA, MMA, Grappling, Improvised Weapons, and any number of other topics related to martial arts. The question is, out of all of these many, many "Pioneers," how many are blazing a path that anyone else cares to follow? How many of these "Pioneers" are pioneering niche paths?
Just because they're not famous or broadly influential in the wider martial arts world doesn't make them not a "Pioneer." Nor does the fact that they're a "Pioneer" make their work particularly useful to anyone or even interesting.
Martial arts pioneering is a lot like wildcatting firearms cartridges. A lot of them wither on the vine or never have more than a small-but-dedicated following. For every ".454 Casull" and ".22 TCM" that makes it to broad acceptance there are 1,000 ".223 Timbs" and ".22 Reed Express" designs that have only a handful of adherents. Same with martial arts "Pioneers."
Peace favor your sword,
Kirk