Just like I don't get 100 IPv4 addresses on my phone, I don't get a block of IPv6 addresses. There is nothing I can do about it. IPv6 changes nothing in that regard, effectively.
Just asked my friend who is on Verizon, when he is tethered to his phone his laptop/computer gets a full globally unique IPv6 address, every device that is tethered gets one. So it already exists.
Sure you can. Do the thing the people whose ISPs give them zero IPv6 addresses do -- use a tunnel broker. Or a VPN provider that gives you a real IPv6 address block.