https://docs.godotengine.org/en/stable/classes/class_subviewport.html
SubViewport — Godot Engine (stable) documentation in English
godot enginesubviewportstabledocumentationenglish
https://docs.godotengine.org/en/stable/tutorials/shaders/using_viewport_as_texture.html
Using a SubViewport as a texture — Godot Engine (stable) documentation in English
Introduction: This tutorial will introduce you to using the SubViewport as a texture that can be applied to 3D objects. In order to do so, it will walk you...