I'm curious about how you plan to work on checked exceptions.
If it's just about ignoring forced exception management, Lombok provides the @SneakyThrows annotation.
I would need something more before I add a new type of extension. Maybe if you could solve the null-check issue.
i.e. rewriting
var x = a.getFoo()?.getBar()
to
var x = a.getFoo() != null ? a.getFoo().getBar() : null
In that case I may consider it for my personal projects, and then potentially recommend it at work once it becomes more widespread and has IDE support.