I expect that this does exactly the same as if you would mount a “local” remote and not related to cache or tmp upload path. In fact, I expect that if I create a virtual disk and mount in on my mac, it should do the same thing.
My assumption could answer the question that yes, it might be limited to fuse.
But I can’t test it right now, I’m swamped (work and personal). I would rule out cache completely from this benchmark as again, it does nothing special apart from a local mount that gets created in the background.