Most interfaces are designed months before anyone uses them. We're building the ones that aren't — interfaces composed on demand, in response to what someone asked for, or what they're about to need.
The biggest decisions are still ahead: what the frameworks look like, where the runtime boundary sits, how we tell a good generated interface from a bad one. You'd be making them — working out how to meet the craft and polish people expect from Apple without giving up the range and surprise that make generative UI exciting.