Just found out you can put 3D objects inside a 2D scene with SubViewports, here's what I got
Just dropped a camera and a 3D object inside a SubViewport, then used that SubViewport as the texture of a Sprite2D. Done, 3D rendered inside a 2D scene.
I'm testing this out in my game, Something Meaningful, a life sim RPG where your consciousness wakes up in a simulated reality after you die.
Steam page if you want to check it out: https://store.steampowered.com/app/4006300/Something_Meaningful/