Mobs can wear Pumpkins but not Jack-o-Lanterns. This is mostly an issue because when an old Xbox One Edition world with the special Halloween mobs is converted to Bedrock Edition, the mobs wearing pumpkins will convert correctly, but the ones wearing jack-o-lanterns will look like normal mobs.

To Reproduce

Change your console to offline mode. Change the date to October 31st. Open old Minecraft Xbox One Edition and create a new world. Once in the world, spawn zombies, skeletons, pigmen, and wither skeletons until one of each is wearing a jack-o-lantern and one of each is wearing a pumpkin. Name these mobs. Exit the world and close Minecraft Xbox One Edition. Switch your console back to online mode and open Bedrock Edition, or just "Minecraft." Convert the world you made on Xbox One Edition. Open it, and you'll see that the named mobs that were wearing pumpkins look the same but the ones that were wearing jack-o-lanterns look just like any other mob.