Microsoft have released Holographic Remoting for the HoloLens2. Holographic Remoting enables developers to create apps that run on PC and stream content to the HoloLens 2 meaning the app can use the local PC hardware for rendering content and display it on the HoloLens. The documentation say it supports devices that run UWP apps and can run on an Xbox One so a Windows app can include immersive content for the HoloLens.
The code is available for developers to be able to add into their apps and the updated Holographic Remoting app is available in the Microsoft Store. The app is also available on Github so developers can create their own customised players.
The original HoloLens also support Holographic remoting but the HoloLens 2 version adds support for eye tracking, hand tracking and QR codes.