Hand-painted VR animation isn't new. Oculus developed Quill, a 3D painting package for the Rift, back in 2015 for its now defunct Story Studio. It was released to the public in Dec. 2016 and updated with a slew of filmmaking features three months ago. Since then, a small community has blossomed with VR artist Goro Fujita -- the man behind the incredible A Moment in Time -- at the helm. There are many impressive shorts online, but my favorite is Alex's Sci-Fi World by Matt Schaefer. It's a neon-soaked delight that you should absolutely watch on YouTube or using a Rift and the original Quill file.
https://www.engadget.com/2018/04/05/alex-sci-fi-world-quill-vr-animation-schaefer/