Update: My company is now embarking on the application process for an invitation letter from Shenzhen's Foreign Affairs Office. This is one of three documents required to get a new (business) visa from the Chinese visa office in Hong Kong to re-enter China: company invitation letter, FAO invitation letter, Covid-19 test result.

If you're interested I will keep you updated on the progress and my experience.

Please note that this will be the very specific use case that was outlined by Shenzhen's FAO in their seminar a few weeks ago: returning to Shenzhen by land from Hong Kong and the implication was that this scenario would not require 14 days quarantine back in China but the seminar and its occasional translations were suitably vague on many points so we'll only get a definitive answer to this by actually doing it. Onward.