The only requirements for selling models is that the model shown in your preview photos should match the model available in the downloaded files. You can upload your .blend or .obj file with whatever you want. Want to sell PBR with basic Diffuse, Metal, and Normals? That's perfectly fine. Want to sell plain models with no textures at all? That's okay too. Just make sure your customers know what they're buying. The complexity of your model and its textures is up to you. If people like your work, they will buy. If not, they won't.
Based on what you've written, you sound like a very new 3D modeler. I don't know what your work looks like, but if you've just started as a 3D artist, don't waste your time trying to sell models. This can be time consuming and not that lucrative, especially for beginners. Build up your skill, see if this is even something you want to pursue. If you view 3D as a hobby, it will be harder to fail at. However, if you decide that 3D is a "business opportunity" and then fail, it's more likely you'll quit.
Again, I don't know your skill level, and I don't want to discourage you from selling models, but you need to be realistic about the quality of your work and your ability to present it to others. If you're an absolute beginner uploading random stuff with garbage topology, pixelated textures, and awful lighting/photos, you won't sell anything and that failure will kill your desire to learn and grow. If you have trouble assessing your own quality, browse this site, or check out artstation. Look at artists above your skill level and below.
Hope this helps, best of luck to you!
