Why would Yamato leave Wano after staying behind to become its protector after Momonosuke and the scabbards failed to protect their country on their own? That's just as bad as saying Tama will get strong enough to join Luffy's crew in a couple of months. Not enough time has passed for that to make sense.
Momo in a grown ass man's body couldn't scare away Broccoli man because he lacked the experience, no haki, no real swordsman skills, almost nothing about him changed expect he can do a boro breath. That the broccoli man had a counter for btw. Nothing will change between now and EOS for Yamato to change her mind and join. And even then, how would she? She has no navigation skills, she doesn't have his vivre card, she has no way of even knowing where the crew is.
Stop coping.