Resin Observer

The resin observer can detect blocks in front of it and break it. It can detect dirt, cobblestone, stone, cobbled deepslate, gravel, sand, pumpkins, melons, sugarcane, and every type of full grown plant (wheat, carrots, potatoes, sweet berries, ect). It will break most blocks, but it will not break undergrown-plants. It breaks blocks with the speed and efficiency of a wooden pickaxe. The resin observer would also have a single slot that can hold a stack of 64 items. If the observer detects air (or lava/water) it will place a block in front of it from its inventory.

Farming

This new block could be used in many ways. If it detects that your wheat is grown, it could break the wheat, and plant a new seed. Your allay could gather the wheat and extra seeds, and a copper golem could sort it. Farming could be completely automated. The resin observer could also be used to make an infinite cobblestone generator.

Mining

You could also make a resin observer minecart which would be useful for mining. The resin minecart would break a block, then place a rail. It would continue to do this until it is out of rails.