What is the ruling on discarding sacrificial animal hides and stomachs in non-Arab countries due to the absence of anyone to accept or buy them, or for the poor to take them?

The hide of the sacrificial animal is part of it. It should not be sold, given as wages to the butcher, or wasted. Rather, the owner of the sacrifice should benefit from it, or donate it, or give it in charity. If it is not possible to benefit from it, but it can be sold and its price given in charity, that would be better than wasting it, because we have been forbidden from squandering wealth. If it is not possible to sell it, then there is no harm in leaving it and discarding it.