So I was testing the snapshot out, and did notice that the crosshair reach appears to be a bit broken.

Made an example here with some mobs. Apperantly you can reach them up to 5 blocks in length. Some of them can be interacted:
Shear the Sheep works with that length.
(Milking the Cow in that length won't work dou.)
You can also interact Trades with the Villagers and Wandering Traders.
Wolves/Cats and other mobs that can be tamed and riden on like Horses will also work.