Can the Switch split a downloaded game between internal storage and SD card?
Solution 1:
I got no sources but since splitting the game in half on PC is hard if not impossible, and that would be with the full control a PC provides, I would guess the same is true on Switch.
So if you want to download Apex (or any game) on your Switch or on an SD Card, you must have that space available, in one chunk, on the Switch or the SD Card.
It is impossible to split the game between two different elements.