Pretty sure we achieved that level of coverage here in the US a decade or more earlier than that. A lot of those same rural customers still rely on the telephone system for Internet access. They might be able to get DSL now, but the speeds are going to be low; often just a few hundred kilobits per second.
So pull modern fibre; as should be done.
And who pays for those miles of fiber? That one customer, because he chose to live there?
I assume you understand that it that's the case, Starlink is a much better option as it won't cost them 5 figures upfront