It’s a handheld PC with a built-in controller. I don’t know how you can say that it’s not a competitor. Plenty of people are happy to deal with Windows for whatever reason. Just because you don’t like it doesn’t make it not a competitor.

If I wanted to make an argument for why it’s not, I’d say it’s because it doesn’t matter what hardware you have, they’re all going to be used to buy games on Steam.