I have this model here and instead of textures I've just assigned materials to different parts of the mesh and gave them plain colors. But when I export it in any format, fbx or obj or gltf, when I try to upload it to sketchfab or mixamo or even try to open it in microsoft 3D viewer, it just shows a blank version of my model. When I import what I exported, it still has the materials but their colors are gone and instead of "Emission" they're now "Principled BDSF". How do I solve this problem? Thank you.
EDIT: Moderators: I have already checked the question provided and all the other questions, they say it's not possible but I've seen people do it on YouTube like Grant Abbitt on his "how to rig the easy way" video. So I've checked quite a lot of questions on this matter but it still doesn't solve my problem. (Also important to mention that I'm very new to 3D stuff)