These components are not used inside any Jetbrains IDEs. Those IDEs are, of course, written in Java and cannot use a browser-based UI framework. This is for "our web-based products like YouTrack, Hub, TeamCity, and Upsource" (per the original release blog post for Ring UI). Those products support mobile.
JetBrains IDEs are not on mobile though. It doesn't matter if they're incidentally accessed on mobile if they're not actually designed to be used on mobile.