It depends. Is 7" measured from the center of my body to the next location? Or is it measured from the tip of the front of my body and the back of my body will end up 7" away from that position? Because the former would likely be useless for breaking into places. My body would make up the majority of the travel distance. I basically would only have 1"-3" or teleport distance to work with. Most walls wouldn't even work.

As someone else said, if I could spam the teleport command, then it would be great. Then I could travel across oceans and such. But I'd have to be careful to not transport myself inside of a boat's hull and get spliced.

The gravel would be great though. With an unlimited supply, I'd just create a turbine which is turned by an unlimited amount of gravel pouring over it. The gravel would have to end up somewhere... Can't just leave it on earth. So I would ask countries - in exchange for the free energy - to build a space elevator/launching mechanism. The gravel would be launched into space towards the sun. This would be a problem in a few million or billion years. I'd accelerate the death of the sun by increasing its mass or maybe my gravel would add too many sunspots. Idk. But who cares. By then we will be space faring. One major issue is I'll die in 50 years give or take. So I'll need to spend most of my time spawning a surplus of gravel somewhere so the governments of the world can continue turning the turbine? Idk. That's a big problem.

Maybe I'd just start a construction company.