Hand pollination would not be economically viable in California because of the prevailing wages. Almond production there is extremely automated and uses very little labor as is, so adding an incredibly labor intensive pollination method would hugely increase prices so as to be non-competitive with other producing regions.

Other bee species might be able to pollinate but there isn’t a consistent model around ensuring they visit the trees the way we have with honey bees. This probably should be developed but it could take years of research if it hasn’t already been formulated.