It would complete the full cycle if we could create/associate Teams/Planner tasks from Project projects.
That way a Project Manager could plan the project in MS Project/Project Web, link it with Teams and manage tasks allocation via Tasks by Planner and have the full view with Roadmap.
Right now you can't do it because you have to manually create the tasks in Tasks by Planner to assign them. You can import MS Project .mpp files, you can link them to Teams but you can integrate Project+Roadmap with Tasks.