I know this may be hard to believe with all the false leaks and rumors spreading around, but I'm going to tell you what I know about the whole remake situation.
I work in advertising, for Nintendo of America. My job is pretty much just to look at the boxes/cases we're releasing and make sure there are no glaring issues. So obviously I don't know a ton about the remake, I only know what I've learned looking at the promotional material that's going to be released.
Pokemon Temporal Diamond and Celestial Pearl will come out on November 23rd worldwide. Unfortunately the games look exactly like Sword and Shield, and from what I've seen there is not much graphical improvement. The base games will not feature any of Platinum's additions, however a Pokemon Platinum DLC pass will be released for 30 US dollars in February 2022. There is a special edition console coming out along side the games. A few of my coworkers were looking over some promotional material for the limited edition system. I was able to take a quick picture on my phone while I walked around the office to get a tissue. I'm sorry this is all I can show without making it obvious who was working on the image