With propagation cups, a loose granular soil could be readily used instead of Sphagnum moss. I'm not at all satisfied with my mediocre success in traditional air layering last year with moss and plastic wrap.

Send me some and will gladly try it and then report accurately.

IMO this would be better than peat moss when used for air layering.

I did a little looking around on the Net and see that coir is being used commonly for air-layering in southern and southeastern Asia, e.g., for mango. I'll give it a try on citrus and a few other fruit trees when it gets warm.