I'm creating a mod in which I have throwable DnD Dice with in-world physics, although since blockbench doesn't typically support the shapes of most DnDice, I only have them as OBJ and MTL files, and, as far as I'm aware, OBJ models for entities is not supported/implemented. I know in 1.12.2 you would register the OBJ model for an item and render the resulting IBakedModel in the same way RenderEntityItem does that, although I'm not very familiar with 1.20.1, and I don't think RenderEntityItem exists in 1.20.1 in the same way it did in 1.12.2 or what the alternative is.
If you have any other answers or suggestions as to how to go about this, I'd also be happy to hear those.