Thank you for reaching out to the Community. Adding an item to the To-Do List is not possible in QuickBooks Online Payroll.
I can see how these additional options and functionality would be helpful for both you and your business and I encourage you to submit feedback. These requests and suggestions are forwarded directly to our Product Development Team for consideration in future updates. Simply go to the Gear icon at the top and select Feedback.
I appreciate your patience as we work through this. If there's anything else I can do for you, please let me know. I'll be around to help you out. Stay safe!