Which case is that? The only one I've seen from Hori that fits the Split Pad Pro is their 'Cargo Pouch', but that one's around $25 (and doesn't look to be a particularly well designed product compared to Butterfox, iofeiwak, or other third party cases that are wide enough to hold the Switch with SPP attached).
And Split Pad Fit is only coming to Japan at the end of September. Haven't seen anything about if/when it will come west. PlayAsia is selling it, but they sold out of the preorders super fast. Personally I don't see the attraction; it's still bigger than joycons so you need a custom case, and if you have to deal with that then why not just use the current Split Pad Pro which is actually ergonomic and already has cases available?