Unbreakable Resource Blocks are blocks that can be broken to drop loot from a loot table and replace the block with the block again, this means you can break the block over and over again. This block can be added via mod or kubejs.

Kubejs Example - This creates a block called New Block that will drop the loot from a gravel block. Using a Wooden Hoe will allow the resource block to be picked up and moved. The drop height modifier can be + or - this adjust the loot spawning from the block

StartupEvents.registry('block', event => {
    event.create("new_block", 'bblcore_resource_block')
        .dropHeightModifier(1)
        .toolToCollectTheBlock('minecraft:wooden_hoe')
        .resourceBlockLootTable("minecraft:blocks/gravel")
})