I suggest to add a procedures like "Despawn Gem " and global trigger "On Gem Despawn". For items of course.
Thank to these procedures it'll be possible for example make a self-plant trees. Just throwing sapling on ground and when this item is about to despawn, then sapling block will be placed.
Other example it spawn baby chicken on place where egg(item) does despawn.
I think that there would be other ideas about this way.
Issue comments
Alright then, there it is.
But one more thing...
There is "Is Current entity" procedure block and as subtype parameter can put "EntityItem".
But how to specify WHAT IS exactly item is?
For example I'll use global trigger "gem expires" and I want to spawn chicken from every egg item that just despawn.
Moreover, I remember some mod, that plant a tree(sapling block) from every sampling intem that's about to despawn on the ground(grass block or dirt).
"On Gem Despawn" -> Global trigger gem expires exists for this
"Despawn Gem " -> Gem is entity so despawn entity works for this