Microsoft OneNote is described as 'Part of the Microsoft 365 Copilot, is a digital notebook application that gives people one place to gather notes and information. It also offers shared notebooks, syncing between multiple computers and devices via Windows' and is a leading Note-taking tool in the office & productivity category. There are more than 100 alternatives to Microsoft OneNote for a variety of platforms, including Mac, Windows, Web-based, Android and Linux apps. The best Microsoft OneNote alternative is Obsidian, which is free. Other great apps like Microsoft OneNote are Zim, Joplin, NoteLedge and sNotes – Students Notes.
The most important feature in OneNote, for me, is the "free-hand" writing feature on any PDF file. OpenBoard allows you to do so. It is also set up to take the whole screen with little distraction on it, so you can work and explain things to your students and collaborators.