I'm saying the competition can only exist because products that actually fill the same need.

If you decide that you need product A, and have multiple options on where to get that, you have competition.

So if you're looking for a Cola, you have options.

If you're looking to play StardewValley, you have options where you want to buy it and which platform you want to play it on, you don't need to buy a new game system to play it.

If you're looking to play the latest Zelda game, you don't have options, you need to buy a Switch.

If you're looking to watch Ozarks, you don't have options, you can only watch Netflix.

If you're looking to just have something playing on TV and don't really care what it is, you have options.

If you're looking to listen to music, you have options, most of the steaming services have most of the music.

If you're looking to be able to text friends, you have options, any phone will work.

If you're looking to be able to iMessage friends and for your case only iMessage will work, iPhone is your only option.

Competition is complex and is more dependent on a consumer needs than just classification of what a product is. In your earlier point you used Apple as an example of a company that can increase prices despite competition, but really Apple is a prime example of a company putting up walls to an ecosystem making it really hard to leave once you're in.

Generally in the current tech landscape there barely is any competition outside openish platforms. But with tech, you often can't look at competition as product A vs Product B. Like while we can say that Window competes with OSx, it's harder to say that a Mac laptop competes with a given Dell laptop (because what you can do with each OS is different to different people).

This is why I like to think of all the tv streaming services as different types of food stores. There is no supermarket that supplies everything, you're forced to have memberships to the single butcher, the single milk man, the single bakery, etc. if you want a particular food, there is currently no (or very little) competition. You can certainly survive on just bread, and people are happy to do that, but that bakery can and will increase prices whenever because they aren't really competing with the butcher.