One of the old shingle machines? Seems something you could rapidly run stuff through would be the best.
Haymakers thoughts were the same as mine about a shingle machine, but finding one might be a problem.
Then I googled kindling splitter and came up with this.
Patent US5355919
I couldn't really figure it out but it got me thinking.
A cabbage slicer. A wide thin wedge horizontal wedge with boxed sides to keep things aligned, with a ram pushing selected blocks through the blade. The ram would have to have a frame attached, slightly longer than the blocks, to pull the block back for the next slice. The block would just drop down on the return stroke for the next slice. stacking the slabs in sideways would finish the kindling up to a point.
The second thought was to split as long of blocks as you can handle, down to gang saw size and run it through like grade stakes, then cut them in kindling lengths.
My 2 cents
Smiley