I departed Geneva Airport on the 25th with Qatar. A power horse through the pandemic, they were on the ball. First tier check-in didn't know: she requested all documents. However her supervisor was quick to appear and approve our boarding passes with nothing more than QR codes from the CHP website (which, I must add, still wasn't updated by evening of the 25th so several questions were redundant and there was no question about RAT). Nonetheless, green QR obtained and that's good enough.
Ironically, an accompanying friend who booked through CX but with a codeshare operated by LH: she was denied boarding as Swiss were adamant that 26th referred to departure time. We all know that's illogical since once HKIA make changes, it will affect the flow for all arriving pax and on the ground HKG could not care less. Alas, Swiss (LH agents in GVA) wouldn't budge. You would think that booking a ticket through HK's "home airline" gives benefit of insider knowledge. In reality, the staff at GVA were useless.
(To be fair, the IATA directive which they followed, was also poorly written: but it should not have been difficult to verify the actual situation with staff on the ground in HKG).
Will now have to see about a hotel refund for the unwanted extra night...
(Said friend has since departed, a day later on 26/Sep, without problems)