The normally super-realistic folks at MiniArt have loosened their imagination and wandered into the hypothetical with the first kit in their new What If...? Series, the Soviet Ball Tank "Sharotank". Possibly based on the Kugelpanzer, that Wikipedia describes as : "The Kugelpanzer (lit. "spherical tank") is a one-man tank built by Germany during World War II. It was captured by the Soviets in Manchuria and is on display in the Kubinka Tank Museum. There is no record of it ever having been used in combat".
MiniArt has a video on their website about the Sharotank, and cleverly inserts their kit model into period photos (or are they real?) showing the Sharotank after capture by the Soviets.
MiniArt also produces other versions of the ball tank: