https://www.bleepingcomputer.com/news/microsoft/microsoft-to-do-update-for-windows-10-rolling-out-with-new-importance-list/

After it was released for Windows Insiders last week, the ability to star your most important to-dos is now available for all Windows 10 users. You’ll find the option after installing the version 1.35.11921.0 of Microsoft To-Do app.

Microsoft says that you can star your most important to-dos in each list and it can be filtered by it's importance. It basically lets you add select tasks to an Important category and the smart list will show all of your starred to-dos in one place.