What will Luffy’s last major power up be?

At this point in the story, I think it’s clear that there are no more mystery power ups left (like Gear 5). In my opinion, Luffy has 3 major power ups left: Advanced CoA, Advanced CoC, and Awakening. After Luffy gained Advanced CoO (Future Sight) and a minor strength boost, he was able to beat Kata and became low top tier. After Luffy gains Advanced CoA (penetration Haki) along with the minor strength boost from Udon, he will be mid top tier. Then, either Advanced CoC or Awakening will make him high top tier, and whichever one is left will make him pirate king level. So which one do you see Oda saving for last?

On one hand, Advanced CoC is special since it should be the most rare and powerful type of Haki, but on the other hand, Luffy’s devil fruit has been a bigger part of his fighting style throughout the series than Haki has and it would be more fitting for Luffy fully mastering his devil fruit to be the final obstacle before reaching Pirate King level. Maybe be able to handle the voice of all things properly? It could not be related to combat but since that is his "very special" perk it may be his final gain in order to enter Raftel or something like that. On the other hand things like awakening and CoC and for sure special but we have plebs like Doffy, Chinjao, Kidd, Impel down guards etc who have it, while voat is something only him, Roger and a kid and his late father have along with some 3 eye tribe dudes probably.