Hyperpigmentation is probably one of the hardest to solve...
There are a few ways to tackle it but you really have to be patient since results don't usually come fast or satisfying enough.
Time takes care of it too....
About silicon sheets, of which I have a vast experience, don't get fooled by the instructions: one single sheet is all you need since washing it once a day with common hand soap will make it last forever, absolutely a nonsense the recommendation to change it once a week (therefore don't waste money on big boxes).
Not the most effective strategy, of some value in order to prevent hypertrophic scars formation and certainly helpful for nicer healing especially if applied as soon as scabs comes off and kept on 24/24.
Niacinamide will not hurt but I am not sure about efficacy.
Better to apply nothing but betadine until the scab comes off, preventing infections is the only thing that matters for a good healing at that stage.
Retin A helps a nicer healing, a tip: if you know you are going to have a surgeon working on you treat the area with Retin A for a couple of weeks before, the healing of the skin will be amazingly fast and nice (much more effective than if applied afterward), if the surgeon is not a dog you might end up with unnoticeable scarring (personal experience), don't ask me why, likely nobody really knows the proper answer...yet.
Dermastamping can do wonders for scars, especially indented ones, but I am not sure if I would recommend it for fresh ones, it might aid in even out pigmentation too.
If you PM me a picture of your scar I might be able to suggest you the best treatment in order to deal with the specific issue.