Upvote:1
In most cases you will be fine; this was the route of choice for many people who wished to return to China when the strict pandemic measures for international flights were in effect.
Mainland passport holders do not even need to hold an onward ticket to be eligible for 7-day visa/endors*m*nt-free transit, since many passengers would choose to take ferry, bus or train for Mainland.
IATA database is a little bit ambiguous on this point:
Passengers with a passport issued by China (People's Rep.) in transit (including overland) to/from a third country for a maximum stay of 7 days.
with the warning that
Visitors not holding return/onward tickets could be refused entry.
which may lead a strict ground agent to check for an onward ticket. Most U.S. airlines from past experiences do not check.
The wording from TravelDoc is clearer:
Visa is not required for Hong Kong. Maximum stay of 7 days. Passengers holding passports or travel permits issued by China who do not hold onward tickets to a third country may be refused entry, unless the passenger is continuing to mainland China or Macau and has arrived from a third country or region.