I'm on metronet, which is a new-ish fiber optic ISP. They're exclusively IPv4 and they default everyone to CGNAT unless you call and complain - in that case you get a static IPv4 for free for a year and then $10/month after that (although another phone call usually gets another free year.)
I specifically asked for IPv6 and was told they don't offer that.
I specifically asked for IPv6 and was told they don't offer that.