Is that in the US? In my Eastern European country, IPv6 has not become directly available to mobile customers. One of our major ISPs began offering IPv6 addresses for fiber customers over half a decade ago; all the customer needs to do is set up PPPoE on the router and the connection automatically gets both IPv4 and a couple of IPv6 addresses. But if you add mobile internet to your contract with that ISP, that mobile connection still only provides an IPv4 address that I assume is NATed to hell. The same is true of internet connections through a large pan-European mobile provider here.