I've soaked old, primed cases in motor oil for over a year and discovered by stupid mistake, that some were still 'hot'

On your center fire cartridges, pull the bullet, dump the powder, chamber the empty case in the gun, and pop the primer. Then if you want to reseat the bullet in the case for collection/show, you'll know it is indeed inert.

Old, unknown powders are good fertilizer on the yard or can be spread out and burned for complete disposal.

The 22 ammo? I'd sit down and shoot it up.