There is currently no official Unity plugin for JoiPlay. While JoiPlay is a powerful interpreter for many PC engines, Unity games operate fundamentally differently and are not natively supported by the app or its current suite of plugins. Current State of JoiPlay Engine Support
Cause: The game is using an incompatible graphics API (Vulkan or DirectX 12) or an IL2CPP scripting backend that the plugin cannot read. Fix: unity+plugin+for+joiplay+work
Ren’Py & HTML Plugins: These are optional but recommended for full compatibility with multi-engine titles. There is currently no official Unity plugin for JoiPlay