[SPOILER ALERT]
The happiness tamagotchi, Hapihapitchi, almost dies towards the end of the movie after using almost all her life force to help Happy remember his true happiness. She is revived by Happy himself shortly after because of his happiness.
No. However, one of the characters goes on a long journey and leaves his dog at home, and the dog gets sad. There aren't any signs of neglect, however, but it may make some viewers uncomfortable.
Lucky the dog is sad that his owner isn't at home, spending time with him. Some of the Tamagotchis look like animals, including Hapihapichi who uses up all its happiness and nearly dies at the end of the movie. It's sad a couple times, but it turns out okay in the end.
The really tiny characters don't get accommodations other than being carried by someone bigger, which isn't ableist by itself but they could've tried to make the happy world of the Tamagotchis easier to live in for tiny little Tamagotchis.
The little monkey child is left at home all alone all the time, because his parents were more focused on their jobs than on him. The parents see the error of their ways and apologize at the end.
Yes, the monkey character has really great hearing/is maybe psychic(??) and can hear things that no other characters can hear. When he was smaller, his peers told him he didn't really hear anything and he's just being mean, and so he thinks nobody will believe him when he says he hears something. We see a flashback of this scene.
Yes, the characters go into a story book that's collapsing around them. This threatens to turn the whole world into a story book. The ground stops existing under the characters, and we see the world dissolve.
The kid characters won't leave the little monkey kid alone, chasing him no matter how many times he tells them to go away. They don't watch him without his knowing, but this may still make some viewers uncomfortable.
Despite one of the characters being from a story book and not being "real," it is never discussed and he isn't unhappy about existing only in the story.
There are a lot of parts of the end of the movie where characters fall off the ground as it stops existing, and it's perilous. Nobody dies from fall damage.
At the beginning of the movie the narrator introduces us to the world, and then doesn't come back to break the fourth wall. None of the characters acknowledge "us."
The happiness tamagotchi, Hapihapitchi, almost dies towards the end of the movie after using almost all her life force to help Happy remember his true happiness. She is revived by Happy himself shortly after because of his happiness.