Since early this year, I have already made 4 trips from HK. Entering HK doesn't feel any different to pre-pandemic days - e-channels are open as normal (do check whether your passport qualifies), no covid-related checks administered, luggage delivery is normally quite fast. Last time my plane parked at the gate at 2220, and I made the Airport Express departing at 2245 with checked luggage!

In theory there meant to be random spot checks whether you have a photo of your RAT test, yet so far I have not heard anyone got checked or seen any such officer in the terminal, so my guess is that this is just a paper exercise and the requirement may be dropped quite soon anyway.

So yes I totally agree going to Regal for the night would be a better option - and up to you whether you want to retrieve your checked in luggage. At check-in at your origin, you can indicate whether you want the luggage checked through or want to get it out at HK, if you check through (I guess you don't really need the luggage for a quick overnight stay) then you don't need to worry about your luggage at HKG - you should be in Regal within 30 mins of disembarkation.