I want to use Cisco Packet Tracer on a IoT project and notice that some devices don't support IPv6. I want to know why the home gateway on cisco packet tracer 7.1.1 don't support IPv6. Everyone has the same problem?
Cisco's Packet Tracer is a training simulation, and as such, often does not have features found on real Cisco platforms, even those represented in the software.
As to why Cisco does not simulate all the features, you would need to ask them, but I would guess they figure the effort involved is not worth the investment for what they expect to use this software for in training.
That said, I would expect to see additional IPv6 features provided in later versions.