Where can I find wave height/period, current velocity and wind speed/direction data at the Qiangzhou strait in China?
You can retrieve that information from ERA5 reanalisys data. It cover the whole world from 1979 until almost the present. The resolution is 0.25°x0.25° and includes many fields that characterize ocean waves. here is a list of available fields for download in the "Ocean Waves" section:



And there is of course, winds data as well.