I have found something weird this week, maybe something is starting to work.
You can only test this if you have bell mobility tethering and Bell home internet also.
I pinged my home fiber's no-ip dns name from my cellphones tether, and I got an ipv6 in reply!
Also works with nslookup (returns both ipv4 and ipv6) What's weird is I have nothing enabled at home in terms of ipv6, it's almost like there's a bridge somewhere that only works internally.
The Bell mobility DNS server that answered was 10.150.10.243 , if that helps.
fyi if you're going to try to connect to a web service running at home, you have to put the ipv6 in brackets, for example:
http://[2001:db8::1]:8080/