To note, they're hiring interns for this, so I'm guessing it's probably mobile, but you never know.
Source: https://careers.blizzard.com/en-us/openings/o1x75fwuGENERALIST ARTIST INTERN
Incubation • Irvine
QUEST OBJECTIVES
An unannounced project at Blizzard is seeking an intern to help create a wide range of assets to help bring our game to life. You will work closely with our concept, environment and character teams to create hard surface and organic props, weapons and possibly characters that are both detail-oriented and consistent with the art style we've defined.
RECOMMENDED TALENTS
Previously work on game projects as a prop artist or an equivalent type role.
Knowledge and understanding of the Overwatch universe.