My girlfriend and I use both differently todo apps. I am using Todoist (https://todoist.com), and she is using Microsoft ToDo, which is integrated into her outlook.
With Todoist, you can use their API to create, update, and delete tasks. So with a little PHP script, you can do this (using guzzle).
When I look at the documentation of Microsoft (ToDo) I get a bit overwhelmed, since Microsoft has a lot of documentation.
Maybe too much.
On Stackoverflow I found a link to the Microsoft ToDo documentation: To Do API overview - Microsoft Graph | Microsoft Docs. As seen in the documentation. Everything goes through the Microsoft Graph API.
Is it possible to create keys to use this API on a personal account on Microsoft?