I looked into using Utterances a while back, but decided against it.

From my blog post [0]: This product requires an external server to be up and online at all times. And while they do promise to be always free without ads, they don't promise to be always available. And while they are open-source and I could always decide to host my own Utterances server/bot, I'd prefer to host nothing at all. This isn't a super deal breaker, because in the end, all content is stored in GitHub Issues.

[0] https://pknopf.com/post/2018-10-13-comments-for-static-sites...