The concept behind Split Meld is not a new one, nor is it complicated. It is for stereo signals. You may have noticed that some fx pedals have stereo TRS inputs with mono L + R outputs. Or two Mono L + R inputs and outputs. Or some amalgam akin to those. There is not I/O standard to speak of.
Split Meld helps retain signal paths in utility with devices such as those.
Split Meld does not sum to mono (you are thinking of an AB/Y Switcher).
Split Meld routes Tip and Ring of the stereo jack to the two mono jacks (think L signal goes left, R signal goes right).
This is the new, smaller take on Split Meld. It is simple. Even more so now. If you play in stereo it may be helpful to your workflow.
Find it at https://www.oldbloodnoise.com/pedals/splitmeld
and from dealers around the world: https://www.oldbloodnoise.com/dealers