The tek you link starts from grain spawn. You don't need sterile conditions at all to propagate loads of mushroom species if you're already starting with a robust dikaryotic culture, especially those of wood-decay (lignicolous) species. That's one principle of "spawn". And there are some dirtier methods that can work, e.g. just dumping spore water onto suitable unsterilized outdoor mass substrates.

But I've seen home cultivators who manage to do things like culture single spore isolates, breed and select dikaryons, clone wild specimens, and fruit very fussy species, all indoors with basic and improvised equipment. That deserves respect.