I could see using this as a base for a water only soil build but you will also need to add in a source of fertilizer and maybe some minerals to buffer ph. It is a bit pricey for what it is. $17.50 for an 8 oz bag seems kinda steep.
Honestly I think a bigass bag of ewc would go a longer way. Investing in a worm factory is an even smarter move. No way compost shipped in a plastic bag could ever be more active than a handful of ewc straight from the worms ass. How long can microbes/fungi survive in a bag? Outside in the cold/heat or sitting in a warehouse somewhere? Not long I imagine...