My professional input, knowing nothing of your shop or location, and all respect intended: hosting DMing "lessons" using other systems like PbtA, SwoN, Starforged, Quest, Kids on Brooms/Bikes, etc. to hone narrative improv skills can often set a foundation of non-D&D preferences — especially when the aforementioned are super easy to get started, thus promoting a higher frequency of game sessions for your fledgling Storytellers/GMs. Hell, offering a free/discounted game room rental to the groups these GMs put together could be a great draw (& good optics) 🤓