...and if all car manufacturers bought engines from the same factory (TSMC), used the same satnav (except one brand, who had a slightly-worse in-house clone), and an accelerator and gearbox from exactly one source (Google search) would you be more concerned about anticompetitive behavior? What if the manufacturers were allowed to produce "accessories" like batteries, tires, and child seats that refused to work in any other car, and actively sued repair shops that weren't official dealerships?

Apple and Google may be competitors, strictly speaking, but the reality is they've pretty well carved up the market between premium buyers mostly concerned with fit+finish, prestige, and compatibility with other Apple devices, and the operating system and network infrastructure for, well, everything else.

It's absolutely a duopoly, and so minimally competitive: either Google or Apple would happily claim leadership status, but neither party really wants the other to go away lest actual competition or government intervention cause them to lose control of their patch of ground.