Since the article is about an Australian court case and comments discussed the US & EU, I was using figures for the whole world, which seems to be 16-18% depending on the source.[1][2] Even if we restrict numbers to the US, 57% is rarely considered monopoly. You'd need significant barriers to entry, and the smartphone market has enough manufacturers that it would be hard to argue that such a barrier exists.
Example: https://backlinko.com/iphone-vs-android-statistics