You don't have to go through the review process for getting an app approved for the app store. But you do still have to apply for a developer key, and buy the necessary additional equipment (which can only legally be Apple hardware), and comply with the associated contractual agreement.
That does mean Apple has a nonzero amount of control over that channel, too.
Literally every piece of electronics in front of me right now is either an Apple device, or connected to an Apple device.
I'm not hating on them. I'm just advocating a realistic perspective on the situation. iOS is a walled garden. That some people (myself included) see that as a net positive doesn't make it not one.
That does mean Apple has a nonzero amount of control over that channel, too.