There’s two parts to laying fiber: Laying the main trunk line and running a line to your house. The main trunk line will be a deeper dig and will have a box or something near the street like the cable and electric boxes you may see around the neighborhood. The line from the box to your house may be a shallow line. The installer may just use a spade to lift up a few inches of dirt and put the line under that. That makes the install quick and easy, but it also means the line is easy to cut if you’re doing any sort of landscaping in the area, including even aerating your lawn.
If you get fiber, think about where you want the fiber line to come into your house. For fiber, you’ll have a simple box at the wall where the fiber comes in. The router will connect to that fiber box with an ethernet cable. Ideally, you want the router to be in a central area so that it covers the maximum range. Pick an outside wall for the fiber installation so the box can be installed in a location that makes it easy to get the router located in a central area. Like this:
Street -------fiber------->Wall->Fiber Box------------------ethernet-------------->Wireless Router
If you can’t get the fiber to come in at a good spot, you may need to install some mesh routers to get whole house coverage. ATT may offer to throw in some additional routers to get the coverage you need.