Don't we have, for example, a Teredo client baked in into every relatively recent Microsoft OS?

My ISP doesn't support IPv6, but I've just checked and a Windows 10 machine was able to do `curl -6 https://ipv6.google.com/` just fine.

And I think I've heard OS X has something as well... not sure, don't have OS X or iOS devices at hand to try it out.

(On GNU/Linux and BSD machines there's a lot of choices, Miredo, 6to4, AICCU from SixXS - whatever one fancies. As usual on *nix systems, setup is manual, though.)