The current spine-godot runtime is designed to work with 2D nodes in Godot, specifically through nodes like SpineSprite, SpineBoneNode, and SpineAnimationTrack. These nodes are tailored for 2D animation and interaction within the Godot engine. There is no mention in the documentation of direct integration with 3D nodes. The spine-godot runtime is primarily focused on 2D skeletal animations, and any integration with 3D nodes would require additional development or a different approach.

valahaha

As you can see in the related discussions, this has been asked several times.
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As @Davide said, a few solutions have been posted. TLDR: You need to use a viewport node to render your 2d sprite. It is not ideal but it supports shadows, lighting and web export (among other things). I did a performance stress test and I could render 80 sprites at 60fps on both desktop and web. It would dip after.