Microsoft today provided a way to get insider builds from Redstone 4 aka what can be the version 1803 of windows 10. If you choose the “Skip Ahead” option you will be able to get RS4 builds from the rs_prerelease branch along with apps updates in Fast Ring.
But as largely expected this “Skip Ahead” option has been only enabled for Windows 10 PC insiders. We asked Brandon, Senior Program Manager on the Windows Insider Program Team about the viability of this option for Mobile insiders. The answer is sad but expected “no”.
Microsoft has not made any rs_prerelease build available for Mobile insiders ever since the Creators update happened. Mobile insiders only received the builds from Feature2 branch with only fixes and very few improvements.
This may further confirm the end of the road for any meaningful feature update for existing Windows 10 Mobile devices. Microsoft may not even consider most of these devices with may be the exception of likes of HP Elite x3 and Idol 4 Pro for the “Windows 10 on ARM + CShell” version of Windows 10 Mobile it is working on.