I prefer mini-greenhouse, and since it's already in a garbage bag
Any pebble like gravel can be used to set the clones on for proper aeration and drainage in a mini-greenhouse.
I've learned to use the soft rockwool, I just bank them with clay gravel for added support.
Rockwool, if used should be used sparingly.
We have found that Stimroot number 2 is most effective in helping to establish roots.
I packed a few boxes of snips and sent them off. I used paper towel and colored tape, them I dipped the paper towel in res water and placed them end for end in spent tinfoil boxes, no doubt from the tinfoil hat party. The guy didn't have the room for all the snips. He forgot them in the cupboard under the sink. When the guy checked on them the box was full of roots. I found this astonishing because I didn't add a rooting hormone. The snips were extra long so the grower could just snip off the thing I attached to keep them alive and root them, the color of the tape indicated strain.
Like I said, Who knows, until you get there.