With Amber and Alysa both done with their Grand Prix seasons, and likely won't be competing again in the fall, their medians are 183.46 and 206.53.
Alysa has proven herself to be a consistent skater, scoring over 200 at every every competition. She has also been consistently making the same mistakes. She's struggled with rotating her combinations in the second half all season, and her 3A has been a very mixed bag as well. She's landed about as many as she's fallen on, and she's yet to get it fully rotated. For nationals, Alysa and her team should work on what jump layout they're going for. At the Challenger competitions Alysa went to, she went with a more conservative jump layout, doing a 2A+Eu+3S in the first half, a 3Lz+3T in the second half, and a 3F+2T in the second half. She was able to rotate those jumps more effectively, usually only getting unders/qs on the 3Lz+3T. On the Grand Prix, Alysa has been more ambitious with trying a 3Lz+Eu+3F and a 3F+2A+Seq which she's struggled to rotate. In this two month period for Alysa to train and peak for nationals, I hope her coaching team really evaluates whether these combos are really worth the additional base value or if they can improve her stamina enough so that she is able to fully rotate those jumps in the second half in competition.
Amber's competition nerves have not changed in the past season. She's a bit better than before in that she finally scored over 200, but she's still very capable of many mistakes which negatively impact her score. With her median, Amber will be going into Nationals in Group 4, where she will need to be in the top 3 to make it into Group 3.
This really helps Karen's chances at the Olympics, since even though her consistency has been highly questionable, based on the Committee's own rules, if Amber doesn't finish at the top 3 at Nationals, Karen will be chosen over Amber by virtue of the fact that Karen's in a higher group thanks to her scores from 2021 Worlds. For Karen's best chance at the Olympics, she will hope that Mariah doesn't score well enough to move into Group 3 and neither does Lindsay. In which case, Karen's Olympic spot will be all-but-guaranteed since at most only three additional skaters can move into Group 3 as a result of US Nationals, and the most likely scenario is that two of the top 3 will be Alysa and Isabeau, so it's likely that only one new skater will be moving into Group 3, which still gives Karen an Olympic spot.