Yes, you can bind something to the other spacebar. Shift, a FN key, backspace, enter, a letter, whatever you want. Normally you would have 8 fingers on the alpha cluster (the letters) and use a thumb for space thus using 9 digits (before someone comes after me for calling thumbs fingers lol). By splitting the space you effectively gain the ability to type with all your digits by giving each thumb a separate key. You can also split the space in more than two keys. Personally I quite like two keys per thumb.
But then you can’t double tap the space bar machine gun style. Jk, sounds smart. Which side do you usually leave for space? I imagine that gets significant more user than the other.
People usually use either their left or right thumb for space (some bring a finger down instead of using a thumb). Whatever side you are used to, you would keep space at in your split space layout. For me that is the right side. The other one is shift for me so it does also get a lot of use, but yes the right one gets used more frequently.