Placeholder for current comment in Trigger (not latest)

Is there a placeholder or a way to get the current comment in a Trigger? Additionally, a way to determine if there is a comment? End goal; include the current public comment in an email if there is one, otherwise just other details from the ticket.

What I don't want is whatever the last public comment was (might not be relevant). There is the condition to see if a comment is present and viewable by the requester, but the only operator choice is "IS", there isn't a "IS NOT" option. So I'm left trying to figure this out with Liquid markup and a placeholder/output field.