I just added Giscus to my site which is the same thing but using GitHub Discussions instead of Issues as the backend which makes more sense.
It's almost perfect except for one almost deal breaker thing (which applies to both Giscus and utterance.es): to comment you have to click through a very scary permissions dialog that claims it can "Act on your behalf" in your Github account, without any qualification. I'm pretty sure the permissions dialog is misleading, but it sucks. I expect that it really cuts down on the number of people willing to leave a comment. And I doubt it will be fixed because Github probably doesn't really care to support this use of their API.