Ah I think that might be a bit challenging for a few different reasons.
To start, the table component provides various utilities for selecting and styling individual rows, but doesn't do the the same for individual cells. I often recommend custom CSS as a workaround for certain styling issues, but there isn't an easy way to write the necessary selector rules.
The other challenge is twofold - "pushing" notifications out to end users and then keeping track of which users have seen those new comments. While certainly not what you have in mind, it would be significantly easier to display a list of the most recent comments.
There's probably a case to be made for adding the ability to select and style a cell via JS, at the very least! I'll talk to the team and simultaneously continue to think about potential solutions and workarounds. 