Hey @JiL,
Welcome to the forum and thanks for asking the question. 
Can you explain a little on how you use this feature and why you find it useful?
How do you get this to appear in Powerpoint? (Can you mention the menu buttons you have to press to see it?)
In Google Slides, you can press:
- View > Show speaker notes
Thanks for that photo. It really clarified what you meant!
That’s not “Comments”, but a “Speaker Notes” pane/window!
No. Collabora Online (or LibreOffice) can’t currently do that. But there is an Enhancement request for it:
Here is the proof-of-concept image they showed:
If you want to keep up on the status, I’d highly recommend you:
- Join the LibreOffice Bugzilla.
- CC yourself to that issue.
- (There are currently 31 people CCed to it.)
That will make sure you:
- Get all the latest updates on this feature.
- + Help the devs prioritize adding or working on that feature!
You’re welcome.