Yes. The book featured here last week, The Art of Plant-Based Cheesemaking uses coconut kefir for both of her longer aged cheeses, but she also stresses experimentation and has made cheeses using other nut kefirs. Kefir is her choice for the wider range of flavours it brings, so maybe substitute a cashew kefir in one of those recipes? Or adapt other recipes.
Many of the additives, like agar are to make the cheese meltable. If that isn't an issue, then moisture reduction is key to making harder cheese, and of course more flavour as well. Karen's book gives good directions for how to achieve this.
If you really want melty, some recipes use tapioca starch instead of agar. The Non-Dairy Evolution Cookbook uses kappa carrageenan for firmer texture and meltiness.
I love a good mentalist. And so does this tiny ad: