How is this even a monopoly? That's like saying "Walmart has a monopoly on selling products at its stores." There are thousands of competing phones with their own software and app stores.
Even in the most egregious days of Microsoft's OS monopoly, you could still choose to install software. Apple makes it basically impossible to do this outside of the context of their app store, which they charge heavily for access to and have no qualms removing or preventing apps that compete with its own. If this doesn't constitute monopolistic behavior, the bar is so high I'm not sure anything would ever qualify for it.
The comparison is this: Walmart and Target are the only two stores that exist. They've also basically agreed to set the same prices on everything. And once you buy from Target once, you must buy everything else from Target too, and if you want to switch to Walmart, you have to throw out everything you bought at Target.
https://www.statista.com/statistics/252678/walmarts-net-sale...
It looks like roughly 60% of groceries are sold at Walmart in the US. And unlike phones, where you can choose Android easily, many regions have only Walmart to shop at.
The answer is more like 25%: https://www.axios.com/2023/04/20/most-popular-grocery-stores