When I was in Charleston a few years ago, I noticed a very strange type of oak planted decoratively around the city. It had acorns, but it had very strange leaves. I can’t remember them exactly since it’s been some time, but I remember that they were small, thin and long, without any of the wavyness/jaggedness/serration of any other oaks I’ve ever seen - there were no lobes at all. I can’t remember the exact length of each leaf but I believe they were about 2 inches long. I think I remember seeing them around Marion Square.
Get the Golden Nature Guide Trees (or any other nature guide) and look up the tree. There are pictures of acorn and leaf for each variety, and it ought to be easy to make the identification.
There’s probably some online site with the same info.
There’s a bunch of oak species without oak-leaf shaped leaves. Long skinny leaves might fit willow oak, which is also cultivated as an ornamental tree:
Your tree sounds very much like what I had in my front yards…right next to the dang gutters. The leaves were slim enough to get through the leaf guards…