Before iphone mobile phones were running Java applets, which were sometimes even compatible across different phone manufacturers and users even could exchange them over infrared. In contrast first iPhone initially had no support for third party software, only web apps.

Sure, at the start, yes.

But then came Java and Wap. You could, in theory, download a jar from a site and try to run it. God knows if it would run. But it wasn't a locked-down app store that bypassing would land you in hot water.