If you don’t have ipv6 internally, you probably can’t access ipv6 externally. 6to4 gateways are a thing. 4to6? Not so much.
I'm pretty sure stateful gateways do exist, but it's a massive ball of complexity that would be entirely avoided if people just used native v6.
Which is purely down to people not testing things before releasing them, because the support is there but there's layers of unnecessary stuff put in the way. Like I had an old ISP provided router that ran Linux, but the management UI was only ever tested against v4 networks so none of the v6 stuff was actually hooked up correctly.
Support in desktops and mobile devices is effectively 100%, but even in embedded hardware there's often full support, just not enabled correctly or tested.