Although Huawei still has to confirm their existence, the Nova 5 and Nova 5i have been both spotted recently on the website of various certification bodies such as ECC, FCC, and 3C. The 3C certification received by the Nova 5 is the latest such event, and it confirms the 40 W charging capabilities of the device.
https://www.notebookcheck.net/Huawei-Nova-5-certified-in-China-40-W-charging-in-tow.421327.0.html