Does anyone know if there is a fast bullet G train from Chengdu to Lhasa?

There is no G train running for this journey. Only the train T22/T23 runs between the two cities. It takes about 43 hours 40 minutes and costs CNY671~712 for hard sleeper, and CNY1065.1104 for soft sleeper. The border may be open at that time. Anyway, you need to pay attention to the news about the policy on the border entry.