Simple portal free gold XP farm

A gold and XP farm on the nether roof that uses no portals and stays in one dimension. Zombified piglins spawn on magma platforms, a turtle egg pulls them to a hole in the middle of each layer, and they drop onto a landing pad where you kill them by hand through a gap under a slab, so you get the XP as well as the gold. One trapped piglin in a boat keeps the rest angry and walking. The layers stack, and most builders stop at four or five.

mobGriefing has to be on, and the turtle egg needs two blocks of air above it. If anything sits on top of the egg the piglins will not go to it, which is the usual reason nothing falls.
Since 1.21.11 piglins spawn carrying spears and can reach you through the gap under the slab. Add a second row of slabs in front of you, or drop your side of the kill room a block lower and hit their ankles instead.
Piglins shove each other off the platform edge and land on the slabs next to you, and that is how people die here. Put a line of blocks or open trapdoors on top of the slabs so nothing can walk across.
Four or five layers is the practical limit. Past that the ones falling from the top die on the way down and the lower layers stop pulling anyway.
If punching the piglin in the boat does not aggro anything, throw a snowball instead. A second turtle egg next to the hoppers does the same job and lets you skip the boat entirely.
Build the magma outline first and put the slabs on after. A ghast can spawn on the open platform while you are still working.