Don’t know if this is helpful at all:
Roughly 7 years ago, while at a trade show, I saw soy hull pellets at the Agribrands Purina booth. However, last summer, when we contacted every feed store we could find in the area and beyond, looking for soy them, no one had even heard of them, including the Purina stores.
The Purina rep who was recommending them at the show was Marc-Andre Blouin, Equine Technical Services Manager, Agribrands Purina Canada.
You might try contacting him, as he should remember having them, and might know if there was a current source. Sorry can’t find his current direct contact information….
SW Ontario, far to the west of GTA