How do you create explosive items?

if you want to make a item like a grenade, then I would suggest making the item a ranged item that deals 0 damage, but has a prcedure linked to it where when the entity of the arrow hits a player, mob, or block(the same procedure should work for all three I think), then the coords where the arrow hit will explode.

Make a procedure to do this.

For this example I will showcase a fused bomb.

Procedure:

On player tick update:

    if item in entities main hand == bomb:

        bombticks = bombticks + 1

    if bombticks == 100:

        explode with power ? at x y z

         remove 1 bomb from inventory

this would make the bomb explode after being in your hand for 5 seconds.