My real goal is Angular Ivy elements with Ionic subcomponents. But if I can get Ionic 4 to dance with Angular Ivy I’m pretty sure I can get the rest of the way myself. For those interested, a good explainer about how to build web components with Ivy is here. You need to use an API that is still private, but the current expectation is that it will be formally exposed in Angular 9.
I’m getting compilation errors when trying to build Angular Ivy + Ionic for production. I’m not sure whether I’m missing something simple, or whether the two don’t talk together yet.