Well, I know that the planner app syncs to todoist: https://planner-todo.web.app/ . I have not used it myself much, but it might be worth a try.
if you want to go full nerdy command line, you can try taskwarrior. While it doesn't support sub-tasks, there might be a way to hack it in. But you might find that you don't need sub-tasks when you use taskwarrior.