Not exactly what you’re looking for but it may be a simpler way of doing something similar enough to what you want. I’m running RetroPie alongside OSMC, I can launch into emulationstation directly from OSMC and quitting emulationstation drops me directly back to OSMC. Installation was pretty simple with macobit’s script https://discourse.osmc.tv/t/installing-retropie-alongside-osmc-rc-the-easy-way/1921
