There's a new single but modular cross-platform, cross-framework codebase which has been developed from scratch.
It covers UWP (Windows, Xbox), WinUI3 (Windows), Electron (Windows, Linux, Mac) and MAUI (Windows, MacCatalyst, iOS, Android and Tizen/Samsung).
Internally we have indeed 4 apps that run on Windows, the decision in favor of WunUI3 was made just half-way during development. The UWP(Xbox) app runs fine on Windows but has a number of drawbacks compared to the WinUI3 version. MAUI uses WinUI3 under the hood on Windows, but with increased complexity in code, so this path hasn't been followed. The Electron flavors are all running, but on Windows, it cannot compete with a WinUI3 app, especially with regards to window management and visual styles.
The next official app from this code base is Emby Linux, the beta is starting right now. Please understand that further plans cannot be disclosed at this time.
Thanks.