I wrote and sold applications on Windows for decades. I never asked for nor received permission from Microsoft to do that, and neither did any other vender I've ever heard of. Windows was never a "walled garden".
It's still amazing to me how huge iPods were about ~10 years ago, considering that they are basically museum pieces now. They gave Apple credibility with people outside of 90s Apple fan(atics). The ads with silhouettes of people dancing were Apple's best in my memory.