It is possible for a Developer to upload a build directly from within the Luna Replay plugin in Unity:
Simply select: Tools > Luna Replay > Building for Playground > Build Linux and Upload.
We recommend testing in Unity editor before uploading to Playground.
Also make sure to have already tagged your game's variables you wish to edit in Playground with the
LunaPlaygroundField attribute. (More on this here)
Or you can export a Playground build locally and upload to Playground manually by following these steps:
Generated a Linux build either using Luna Replay or manually using Unity.
Navigate to Luna Playground in your browser and ensure you're signed in.
Drag and drop the compressed folder containing your Playground build to the Cloud icon in the apps page in Playground.
You can read more on uploading builds here.