The eagerly anticipated OnePlus Watch is said to have dumped Google's WearOS according to a reliable leaker. Instead it will run an unspecified operating system that is presumably a bespoke solution.
https://www.notebookcheck.net/OnePlus-Watch-will-skip-Google-s-WearOS-design-likely-based-on-Oppo-s-forthcoming-circular-Watch-RX.503326.0.html