I've tried to scale down a single fruiting medium to 100-200g, and it keeps failing time after time: at best, I get small needle-sized fruiting bodies (hypsizygus tessulatus, post picture) or primordia and then small malformed underdeveloped fruiting bodies (pleurotus eryngii, inline picture). Then development just stops. Medium is enriched (sugar) alder chips, contamination starts developing long after growth is stalled. Is it really scale problem? What's the reasonably smallest batch size?
Definitely doable! I learned how to grow through a class hosted by my local myco society, and they made a point to show us oysters growing in + on all sorts of wacky things. Shoeboxes, laundry baskets, water-damaged homes, etc.
Just hard to beat the cost of plastic grow bags at scale :).