Actually applying for a Z-visa in HK if you are not a resident/citizen is always touch and go regardless of nationality.
The strict rules are that you need to present proof of HK citizenship/residency in order to apply for a Z-visa in HK instead of your home country. However an exception may be granted provided:
a. your China company was able to secure an invitation letter stating HK as the place of Z-visa application
b. the consul official based in HK chooses to accept the application
In short, you’re essentially asking the Chinese officials to bend the rules to let you do the application in HK instead of France; this does leave you at the mercy of the officials and no guarantees what will happen.
There have been stories of people who have the requisite invitation letters for HK but were still denied my the consul official after being asked for proof of residency, so having an HK-invitation letter is not enough.
Most of the time there’s no issues for approval, but the consul official is having a bad day then you’re really in for it.