As of now Samsung hasn't officially said anything about Android 10. There aren't any confirmation from Samsung about any Android 10 beta program or when Android 10 is going to be released for Samsung devices. As from previous OS updates timelines and some reports, there might be an beta program soon for Newer Samsung Flagships devices. So For now there are no any news on Android 10. So we'll just have to wait and see.
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Google's Pixel phones are running a near "vanilla" build of Android Q, meaning there's little to no changes to the default Android UI or customizations that could cause app crashes or less than favorable performance issues. Samsung would have to first test functionality with the One UI and with the Knox security platform to make sure that any official release of Q on the device meets specific requirements.
Expect update to Android 10 around when new S models will be released (around February). Check update history of S9, S10. The bulk of Samsung’s Android 10 updates to land in early 2020
T-Mobile S10 and Note 10 Series are already on Testing Phase for Android 10. So stay tuned!