What do you mean by bioactive? Are you thinking on housing multiple species together or simply increasing the microfauna? You could try and add springtails, but keep their numbers down so they don’t deplete the substrate’s nutrients!
clean up crew like isopods. Hercules' are pretty docile afaik so U have lots of options. My friend cohabs zebra isopods, hissing roaches, earthworms, and interchanges mating pairs of hercs