Android Q Beta 1 landed on the Pixel smartphone series earlier this week and according to a Google Product Expert on the android_beta subreddit, Build 1 will remain exclusive to Google's smartphones but other OEMs should be expected to join the OS version's testing and development in later Beta versions.
Android Q is currently planned to have up to six testing stages including Beta 1-through-Beta 4, as well as two release candidates in the form of the Beta 5 and Beta 6 stages. The final release is expected to take place in the third quarter of 2019.
When can other devices be expected to join the beta?
For its own smartphones, Google has a pretty clear idea as to when the different Android Q testing stages will take place. Beta 2 will commence in April and should be followed by Beta 3 and Beta 4 in May and June, respectively.
The source was unable to provide any stable timeframe as to when other OEMs will offer Android Q beta builds for their devices but confirmed that Beta 1 will be limited to the Pixel series. In other words, third-party OEMs won't be joining the beta program earlier than April.
Some OEMs will likely get a head start over others and could join the beta program as soon as Beta 2 launches in April. To a degree, this depends on how close their relationship with Google is and how fast they may want to introduce Android Q firmware updates to their flagships once the OS version will be ready for a final release in Q3.
Much like in previous years, eligible Pixel owners can now sign up for the Android Q beta program through Google's own channel. Google already supports the entire Pixel lineup from the first generation to the Pixel 3 so there's no need for the software giant to add any other devices to the program. But as noted by the source, other OEMs will offer their own beta programs and registration pages later down the line, and users will have to meet their specific requirements before participating in beta testing.
What other OEMs are expected to join Google?
This year the Android Q testing phase is said to encompass more smartphone brands than ever before, as confirmed earlier this month by Project Treble engineer Iliyan Malchev. Sony, OnePlus, Essential, OPPO, Vivo, and HMD Global with the Nokia brand are all expected to prepare their own Android Q beta programs for their user bases. For non-beta participants, an early involvement from the OEMs could translate into more timely software updates in the future.
It's important to note that the third-party handsets which will eventually join Google's Pixel phones in testing Android Q are all expected to run stock Android OS. In contrast, devices running custom firmware based on Android OS will likely start being updated to Android Q after the first stable build reaches the public.
In many cases, proprietary UIs receive additions that may have been built around new features added by Google to its stock mobile OS version. Other times the custom UIs can include brand new software features unavailable on stock Android OS. These additions take more development time and proprietary UI elements usually require additional testing which doesn't concern Google itself.