The VR editor is deprecated and hasn’t been updated by Epic in a long time, so it still only uses features that are available in the legacy SteamVR plugin. The VR template on the other hand was updated for 4.27 to show off features in the new OpenXR plugin. Epic isn’t supporting the SteamVR plugin anymore, so they have not set up the template to be compatible with it. 4.26 and older versions of Unreal have a different template project that supports the SteamVR plugin.
There is also a Valve-made example project available designed just for the legacy SteamVR plugin.