Regarding Yamato, it would be amusing if Kaido is unaware that Yamato is a female. Cue shocked-Kaido face when Yamato reveals herself to her father.
I like this but how would that work? I was thinking Kaido was the one that pushed her to be male because he wanted a son and that backfired on him when she chose to take after Oden.
Unlike a mother who gives birth to a child, the father does not necessarily have to be there when the child is born. In Kaido's case, given the amount of times he was caught by enemies, the amount of times he was tortured, the amount of times he was sentenced to death, the amount of times he attempted suicide and how it was also stated in his introduction that he lived as a prisoner, it could be that Kaido was not present when Yamato was born and may not know her true gender. In addition, Kaido is the captain of the Beast Pirates, so he also has those responsibilities to take care of. Yamato's mother may have fashioned Yamato to appear as a male (fearing Kaido would not accept a daughter?), lied to Kaido that Yamato was a male and supported Yamato in her reverence for Kozuki Oden. This is all speculation but I just find the prospect of Kaido being oblivious about the gender of his child too hilarious to not entertain. Kaido doesn't seem like 'father-material' based on what has been shown of him and the beating he gave Yamato upon mentioning her desire to be Kozuki Oden (probably when she was younger and inspired by the legendary hour long execution) likely created a distance/rift between their relationship as parent and child.
We have only had two chapter featuring Yamato but I am finding her character immensely fascinating already especially with the themes of 'identity' and 'inherited will' seemingly central to her character. It has been a long time since we have had a character so imbued in possibility that it is hard not to theorize about the potential existing for Yamato.
I also feel the Octopus that stealthy boarded the Thousand Sunny and casually integrated with the background of the crew before voicing its greeting and summoning the Koi Fish at the start of the Wano Kuni arc could be connected to Yamato. That Octopus did seem strangely interested in Luffy. Yamato knew about Luffy from Ace and likely also knew a bit about Luffy’s personality from how Ace would have described him (Ace did like to talk about his 'younger brother'). Expecting Luffy’s arrival, Yamato could have sent the Octopus to wait near the waterfall and to inconspicuously board any pirate ship that came near to Wano Kuni until it found the ship Luffy was on board (Straw Hat pirate flag) and when it did, it was to assist them. The relationship Yamato has with the Octopus could have been born from the lack of support and connection Yamato has within Wano Kuni. If Yamato couldn’t befriend any of the Beast Pirates, she may have opened up to the animals within Wano Kuni. And considering Yamato's ability in evading capture and notice, the Octopus could have learned its stealth skills from Yamato.
IF Yamato were to join the Straw Hat Pirates, her role could be "stonemason" or aspiring stonemason (Luffy was excited at the idea of getting statues in chapter 302 and 303 and of Kyros's statue in chapter 704). Through Oden's logbook, Yamato could have learned that the Kozuki clan were a clan of master stonemasons and subsequently became interested in becoming one. Given that the Kozuki clan knowledge of Poneglyph making, writing and reading died with Oden, Yamato may gain the desire to help revive the art upon learning that Kozuki Momonosuke and Hiyori are still alive. Oden could have detailed in his logbook that he left knowledge and instructions about the Kozuki art on Laugh Tale in case he was unable to pass on the knowledge to his children. There is also the possibility that part of Oden's logbook was burned out and Yamato curious to learn more about the contents of the missing story of Oden may decide to travel with the Straw Hat Pirates in order to fill in the gaps by having her own adventure to Laugh Tale and the places in between.
Alternatively, Yamato’s story could be to act as a defender of Wano Kuni and be their Guardian once the Wano Kuni arc is over.
Personally, at this point I am hesitant to believe Yamato will be a Straw Hat Pirate nakama but I can't deny that much like the rest of the Straw Hat Pirates, Yamato has been revealed to be a romantic just like them. Very excited to learn more about Yamato and whether she is aware that Ace had been executed.