On Android wear, doit.im has got the following minimal supported:
- All notifications can be surfaced on the watch and dismissed in Android wear default UI for all android apps.

However, as a GTD tool, here's a few more things that's nice to have (these will involving some dev costs building an Android wear app running on the watch)
- Quickly create a task using voice on the watch (this can be achieved by replacing Google Keep as the default note-taking app)
- Open the task list on the watch (again, a similar behavior replacing Google Keep on watch)