My impression is that Apple Care for iPad Pro covers all Apple iPad accessories? In other words, if you bought Apple Care for iPad 2 months ago before you got the Apple Pencil, it should cover it for as long as the iPad is under Apple Care. Is that not the case? I recall seeing the details of Apple Care where it covers the Apple Pencil and keyboard folio/ magic keyboard as well.
Anyway, 1 thing I noticed is that Apple Care starts its 2 years coverage from the time of purchase. So if you don’t buy it immediately, and drag till you are approaching the date where you device will no longer qualify for Apple Care, you can extend the warranty further. In my case, I noticed that the Apple Care I activated on the last day of the qualifying day extended the coverage by 2 years. If this is indeed the case, then it makes no sense to buy Apple Care at the onset.