A video that was briefly present on the Facebook page of OnePlus India reveals that Marvel Studios will team up with the Chinese brand for an Avengers-themed limited edition of the upcoming OnePlus 6 flagships. The video has been removed shortly after being posted, apparently because it was a test video that should not have been shared online.
https://www.notebookcheck.net/The-Avengers-themed-OnePlus-6-is-coming.294500.0.html