Comment by floren

The Grant County Public Utility District in eastern Washington (and presumably PUDs elsewhere in the nation) did exactly that. They built a fiber network throughout the county (physically large but pretty sparsely-populated), although they don't provide service directly to customers--instead, a healthy number of local ISPs still exist in the area. If fiber isn't at your house yet, there are also a few WISPs, which were easy to stand up because of the fiber.

https://www.grantpud.org/getfiber