Yes true but I've just accepted that the Air has a $1 dollar store keyboard on it. I docked my Air for home so have it permanently connected to a mechanical with tactile keys. So much better. If I have to, I will bring this keyboard with me, that weighs more than the Air itself.
Also another reason that I don't want to use the Air's keyboard is to prevent shiny keys. You will get less resale value when you sell the laptop down the road if your keyboard has much more wear on it.
I completely understand your frustration with the shiny keys. It is pretty inexcusable in laptops of the cost and quality of MacBooks.
That being said let me shift your focus a bit?
Shiny keys happen on all MacBooks with just a little use or within 2 months of regular light use. If that is so resale value will not factor shiny keys because it is considered normal wear that is unavoidable. Sure, If you have a 3 year old Mac with a brand new looking keyboard light get you a few bucks more but it really won't make a huge difference.
If resale won't be affected by shiny keys since it is a guarantee on any Mac that has been just lightly used then you don't need to worry about it. In fact, until Apple makes MacBooks with a better plastic key in the keyboard your resale won't be affected. If Apple changed the plastic in the keys on new MacBooks that would be a factor but it isn't for normal expected wear.
I also disagree with the idea that is is a dollar store keyboard. It is not! I have had cheap keyboards on various laptops, Chromebooks, etc. This is an exceptional keyboard with incredible backlight with no light leaking from the keys. The accuracy is amazing for me. The feel of the keyboard is just about perfect for a thin and light. I love this keyboard and it rivals another favorite which is the Surface laptop keyboard which might be my favorite and the M2 MBA a very close second. The thing is my surface never had shiny keys??
Things that will affect your resale value,
Battery health.
Wear to the finish of the case on any surface, scratches, dings, etc.
Scratches to the screen.
These are the things that will affect your resale value far more than shiny keys.
MacBooks seem to hold up well over time as long as you are careful and keep your laptop in a case when not in use as much as possible.
If you focus on things that you really can't control and that are pretty much guaranteed to happen over time it will simply create anxiety and fear and potentially harm the enjoyment of your MacBook. Just do your best with common sense methods to keep your Mac in the best condition possible while getting the most use possible before you sell it.
Otherwise I think considering the weight and limited portability with the remedies you have made defeating the entire point of an Air Laptop I would seriously consider a desktop option as new releases like the new Mac mini are pretty affordable. Then your peripherals would mostly be your own and then it is just the Mac mini or iMac which would be much easier to keep in good condition for resale.
BUT you do you. I am just considering stress and well being. I think it would greatly lower your stress if you simply had a desktop or if a laptop is important and the shiny keys and keyboard I general are unacceptable to you or you may have to consider a different type of laptop like a Windows laptop.
I have had countless Windows laptops and Chromebooks and the only time I have ever had shiny keys is on MacBooks with the exception of the printed keycaps on really, really cheap laptops. Any decent Windows laptop or decent Chromebook for the last at least 15-20 years I have never experienced any deterioration in the keys or shiny keys. On any modern and mid range or higher Windows or other laptop I never had shiny keys and my MacBooks were the first. My M2 MBA took the least amount of time. Other m series MacBook have had similar shiny keys but it took longer like 6 to 12 months instead of 2??