The main thing I want to hide in minimized comments are "+1 fix this plz!" comments on bugs, comments that add nothing above and beyond a thumbs-up reaction. The "reasons" Github offers for minimizing comments are: Spam, Abuse, Off Topic, Outdated, and Resolved. "+1" isn't exactly any of those. (I guess they're kinda "Spam" but they're not unsolicited commercial messages.)
If you don't have anything more to add to the discussion, but it seems like the issue is not being considered, a "+1" comment seems like the most effective way to communicate the need to the devs.
Ideally a thumbs up reaction would do the same thing, but does it? Do devs use the sort by "reaction" feature in real life?
I have not yet had the chance to be on the other side. I'm pretty sure I'd check that list occasionally, but I bet I'd forget a lot of the time. Especially if I had a busy project. Sorting by "most recent" or "number of" comments would be more likely. And that would make a "+1" comment more effective.