Looking at a reference image of an apple (a red one), there seem to be 2 parts - "Skin", and "Spots", and they both seem to be "vertically oriented", if that makes any sense - they look stretched top to bottom. So, the "Skin" can be generated by using a Noise Texture (Stretched on the Z axis using a mapping node) as the vector input for a Wave Texture - the Mix node is to "soften" the effect (otherwise it's too "brainy"). The skin base looks like this:
The second component, the Spots, can be accomplished by using the Distance output of a Voronoi Texture. I stretched this on the Z as well, to make the "dots" more realistic. Note that we are using Generated texture coordinates (as opposed to UV), the downside being that not all procedural textures are "the same" in all directions. The result here is that there is unrealistic stretching around the middle. In this case, we can "hide" it pretty well by not mixing in the spots very much, and viewed from a distance, it should be pretty imperceptible. The spots base looks like this:
Here are the skin and spots after coloring:
Since the "skin" texture is detailed enough, you can also use it as the basis for a Bump Map. Notice I mixed the value heavily with white first, as we want the effect to be super subtle. Bump map effect on its own looks like this:
And here's the whole thing put together. I also used the "skin" texture as the basis for a Roughness Map, but it's probably not necessary unless viewed extremely up close. Just use a value of 0.2 on the Principled BSDF or something similar:
This is just for the outside skin, mind you, you will have to make a separate texture for the "inside" of the apple, and apply that to the faces that are "sliced".