In 2018, Eugene from the Radio-T podcast (aka Umputun) released a minimalistic commenting engine. The simple self-hosted system is easy to embed into a blog, article site, etc. The list of features is impressive in its variety.
Under the hood: Go, Bolt database, Preact & Redux.
Remark42 powers comments under the posts on this blog.
The closest alternative is Disqus, but you don’t own the comments there.