Sure. You could sell your textures, share it, use any way you like. When using outside Unity, it may require to move some of your maps channels in image editor, according to your target engine and shader. The exported result maps are common for Physically Based Rendering (PBR) shaders: Albedo, Normal, Ambient Occlusion, Glossiness, Emission, Heightmap, Transparency, and Specular/Metallic, depends on chosen workflow. It is also possible to export material ID masks, which could be handy for shaders with color tint variation of the part of the texture.