Paint3D allows you to paint the model using a spray-can, for example, directly onto the texture while in 3d. You can still extract the textures from a model and paint in 2D in photoshop, for example, because the .3mf format is simply a zip file.
However, I expected more format support, and for display in web pages expected to see the gltf format being used.
As it is, Paint3D only supports the .fbx and .3mf format, which isn’t so useful for me.
Paint 3D doesn’t really share models, other than as an upload to remix3d, which is similar to Sketchups upload to the 3D warehouse.