I'd be curious to know if Huawei phones and network devices are currently being used for surveillance in Hong Kong.
I'm guessing you're curious if the Chinese government is using some hidden backdoor in Huawei products to spy on Hong Kong residents who would otherwise be acting privately.
Backdoors in the phones seems highly unlikely. Considering that the government can simply listen in at the cell towers and data centers there is no reason to risk the reputation and thus influence and reach of a Chinese company like that.