If you explode Powdered Snow in any version between beta 1.16.200.52 and beta 1.16.220.52 with TNT, the block variant will end up dropping as an item.[1]
Wither
When a Wither destroys a Powder Snow block in 1.17.0.50[test], it will drop it as an item.[2]
Piston Removal
From Beta 1.16.220.50 through Beta 1.17.0.52, powder snow could be obtained as an item in survival mode by placing it in a space occupied by bubble columns and water, then activating a piston, resulting in the powder snow block dropping as an item.
Powder Snow inside of an inventory.