- The Mythical Zoan class is functionally a Zoan and Paramecia fused into one and Luffy's Awakening confirms this. He gains both the power and recovery boost of a Zoan Awakening and can give the environment temporary rubber effects like Law and Kid's Awakenings (different from Doffy and Katakuri who produce their materials). It's rarer than Logia for a reason...
- Zoans having a will of their own is no surprise. Gifters are essentially two freaks sharing one body. Lasso the dog cannon and Frunkfreed the elephant sword wouldn't work if they weren't alive to hear commands and transform. Just like Lucci claims he gained more carnivorous taste, I imagine the Nika DF influenced its past users just enough to spend their lives running away from the World Government. But Sengoku the Buddha is no saint and instead a top enforcer of IM's world order, a Zoan hardly overwrites your own personality.
- The steam and blood pumping of G2 + giant limbs of G3 + the seamless form shifting of the G4 forms. The overwhelming haki energy made possible by unlocking advanced CoC, a step up from the emission CoA he learned in Wano, which required the strong CoA and CoC bases he gained during the time skip. Luffy didn't just stumble upon G5, it's a culmination of all his hard work and creativity.
Not going to lie, I love this development. The idea that the suffering people of the world have been waiting, hoping and praying for somebody to deliver their collective ideal of the Sun. Some civilizations worship it directly like the Shandian sacrifice rituals or Elbaf Winter Solstice fasting. Others merely idolize concepts like salvation and freedom represented by it like the Shadow-less victims of Thriller Bark who can never enjoy sunlight or the former Fishman slaves who bore the Sun symbol desiring their people could one day live free on the surface.
The Skypeians praying to the Sun for a god-like figure to clear the skies and strike down the cruel god Enel. Who's Who praying for his freedom in a cell. Toko sending her wishes up to the heavens in the Fire Festival. THEY created Sun God Nika. It was at this point you knew Luffy was anything but ordinary. (We'll ignore how he cruised through East Blue with a power so rare it was considered a myth while enemies like Kuro, Krieg, Arlong had to contend without it.) And we know anything humans can imagine is a possibility in reality.
The Sun God is the will of the world, manifested in a Mythical Class DF. Luffy merely inherited it, it's latest user in 800+ years of trying. It just turns out the boy born on Dawn Island coming from the East (cardinal direction of sunrise) Blue, sailing in the Thousand Sunny, defeating the dark forces whether pirates or the WG, bringing peace and parties and a new day, desiring to live as the freest man on the seas best embodies the people's ideals. Because One Piece is a world larger than life: a world where legends can become true.
While the connection between the Sun and the power of rubber has not been made clear, we can probably forge some based on characteristics highlighted over and over by Luffy.
- Boundless. As the Sun is an ever-changing ball of plasma, the form of rubber is not rigidly defined and can shrink or expand past its boundaries. The element of freedom. The element of adaptation. No matter what obstacles get in the way, rubber can change its shape to best overcome them. Luffy quite literally extending his hand to reach new heights.
- Happiness. As the Sun is a symbol of radiant positive energy, rubber is considered a funny material. It's wacky movements and designs can bring a smile to people's faces, even outright turning a frown upside down by tugging it at from the opposite direction. It evokes the universal sense of joy associated with the warm rays of sunshine for everyone basking in Luffy's presence.
- Rebounding. Rubber always bounces back and Luffy always gets back up after getting knocked out. It not only represents his strength of will but the power of never-ending human vitality. Like the powerful endless energy constantly poured out by the Sun, Luffy's struggles lift not only himself but help and inspire all those around him.
I look forward to seeing how crazy the Sun Cult gets when people realize their messiah is here.
Kaido might honestly be Joy Boy's #1 fan.