Eroded blocks would drop items, then the items would go whereever the default flow takes them.

Additionally, they could convert back to blocks on item despawn 🤔

After 4 years, I still don't see a viable way to implement this. Items fly all over the place. 😆

What about the item converting into a block after the item stops moving, and then it is placed into the next block it finds in the Y-axis, maybe could be "fancied" by making it a falling sand version of the block?

Edit: The reason I think it should be right after the item stops moving, is because it would avoid stacking with another block item overtime. Although I wonder if this mechanic in general would affect player-dropped items, if so, is it possible to avoid that?

I need to do some playtesting of this. I wish river deltas would generate, but I suspect relying on the existing item movement will result in a scattered mess instead of anything approaching an organized delta.