Can you roast soybeans directly in a popcorn popper or microwave?
No, you can't cook dried beans just by roasting them. All this would do is it dry them out even more and that wouldn't make them more edible. Indeed, dried beans are used as baking beans to weigh down pastry during blind baking and they don't pop like popcorn.

All recipes for roasted soybeans require some combination of soaking and/or boiling before they can be roasted.

(Note we're not talking about fresh soybeans here, those are green and succulent.)