If you don't currently have IPv6 service, have you looked into something like Hurricane Electric's IPv6 tunnel broker? [0] It's how I got my first IPv6 subnet, and worked really well for me. I stopped using it when Comcast finally got around to providing IPv6 for non-business accounts.
It’s been like two decades since i last used this but at the time HE 6in4 tunnel required static ipv4
It has also been about that long since I used the service. According to my very, very distant memory this requirement was implemented by having you punch in your IPv4 address into a form to configure their end of the tunnel. I know for an absolute fact that Comcast was not providing me with a static IPv4 address, and the HE.net tunnel worked just fine.