I would advise to be open-minded about alternatives here.
There are amazing shops with every kind of kitchenware you could want, like King Tat in Wan Chai. Even Wing On has a good assortment of things, and it's fun to discover other brands or kitchenware from places like Japan or Korea.
As for medicine, Hong Kong is actually quite easy, because pharmacies don't require prescriptions. To get medicine, you either go straight to a pharmacy and ask for what you need (generic names) or you can visit a family doctor (GP) and as part of the consultation fee, they will include the needed medicine. The only thing from the US I've ever missed is neosporin.
Like someone else said, if you're not petite or have big feet, definitely stock up on clothes and shoes at home, and keep in mind that for 70% of the year you will want to wear as light of clothing as possible.
But definitely reconsider if you want to move to HK right now. You need to be aware that you are moving to mainland China.
Also, there are dozens of similar threads on here - search for them as some have very extensive lists of stuff that you cannot get.
Recently I’ve found it hard to find the variety and quality of only two things in HK vs the US:
1) Medicines, vitamins, supplements - much more variety and higher quality can be found in the US. A true hassle finding effective cold and flu, pain meds, allergy medicine etc over-the-counter
2) Bed linen - overpriced and hard to shop for good bed sheets etc in HK; also things like comforter clips don’t exist here
It’s good that these days Amazon, iHerb and US department stores like Macy’s can ship pretty much anything to Hong Kong and its easy to find things (vs hunting in multiple stores in HK)
I’d also bring some local foods - like jams from your state, chocolates, spreads, whatever is famous in your area. A taste of home, will help when you get homesick! But make sure you don’t put jams in your carry-on and don't bring any meat!
Oh someone mentioned OXO tools - a small selection exists here (can find in SOGO for example) but at higher prices (basically top retail price, no discounts) compared to US.
If you color your hair with home coloring kits, bring a few...there are many, many shades of black but very few of brown and maybe 1 of blonde. Can get it done at a hair salon but can be pricey and not all places are good with subtle shades of western hair colors. Some places charge more for shipping due to the ammonia and other chemicals in the kits. Or change your hair color- if you have always wanted black hair, this is your moment.