PinePhones on assembly line

[Potts]

made in China?

Yes

Then let's hope they use standard technology "clean room" processes, including manual handling with rubber gloves.
When I got my BH phone, I did wipe it down with an alcohol-soaked tissue (good thing there was a screen protector on it with the next-to-last film on top of that - nice "touch", Luke ;-}  ).

You shouldn't worry about the virus surviving the long trip to your country. Shipping is taking longer than expected and the phones are being sealed in their boxes probably many days before your unpacking. No virus will be on your phone. You should be more worried about your delivery man coming to your door, and coughing on your parcel

Or HW backdoors.

This in theory could be a concern but nothing is 100% secure. We have to pick and choose the risks we are willing to take, Pine64 is such a small company that I'm reasonably certain the Chinese Government has not installed a backdoor- far more useful and likely is something more mainstream, like an Iphone or Android device.