I barely remember this film. It could have maybe been made in the 90s or 2000s. It was animated in a cartoonish style, and I'm pretty sure it was a movie.
I only remember the very end of the movie. There was some organization, scientists maybe, trying to grow grass on the moon. They had some sort of ship that dispersed grass seed that was about to take off. The protagonists, male and female, who may have been siblings, were trying to stop this ship from taking off, I think. I'm not sure why. I remember that the protagonists had a small pet dog. This dog somehow ended up inside the ship right before it took off. The protagonists were probably trying to stop it for this reason. The ship took off with the dog inside.
The scene cut to many years later. It showed the two protagonists as being elderly, and one is watching the TV. On it, there is a news report showing that the moon, now a pale green color, has been repopulated with grass. There is live footage of the moon, and we see that the dog is still there, and it runs towards the camera.
Side note, these scenes had a very bittersweet undertone, and the ending was quite sad. I only remember other snippets of imagery that may be from the movie, such as the protagonists living in a large brass tower (?), but I am also pretty sure that the movie had a steampunk apocalyptic sort of theme.