In a 2020 demo reel from Hong Kong based company Simage Animation and Media Ltd, a mysterious animation has surfaced featuring Astro Boy and Tezuka Star System characters, including Atom, Pluto, Son Goku (My Songoku, not the Dragon Ball character), Rock Holmes, Hosuke Sharaku, Hyakkimaru, Unico, Ambassador Magma, Shunsaku Ban, Siddhartha (Tezuka's Buddha), Triton, Big X, and Princess Sapphire.
The animation depicts Atom and other Tezuka Star System protagonists battling Pluto in a fictional Japanese city.
The purpose of the animation is unknown. It does not appear to have any connection to Astro Boy Reboot or Team Phoenix (which was released after this animation was made).
The demo reel featuring this animation can be viewed in the sourced link. The timestamps to view the clips are as follows: 0:18, 0:59, 2:34, 2:46.
I don’t have a LinkedIn account to view it, but my friend found a LinkedIn account for one of the animators of this project. The project is called “Tezutopia."