I feel like getItemDetail whether it be for the turtle or the inventory peripherals, should also include whether the item is a fuel item and how many items it can smelt or how many ticks it smelts for, either way I think you can convert that.

{
count = 1,
displayName = "Block of Coal",
maxCount = 64,
name = "minecraft:coal_block",
tags = {},
isFuelItem = true,
fuelCount = 80
}