Yes, the current charger is using the same technical principle and compatible with a charging protocol, regardless of the power size it can be used, but because of the difference in charging power, it will lead to a slower charging speed, which mainly depends on the power supported by the device and the change in the power of your charger, which affects the change in charging speed.
Xiaomi 66W fast charge can charge Huawei. But the charging agreements are different. Only normal charging speed.
I don't think so. The data and protocol of each mobile phone fast charge are different