I'm also stuck with Disqus and want to switch for the same reason. Here are some ideas to get your own comment system running: StaticMan[0], Isso[1], Netlify GoTell[2]. This article[3] brings up some more ideas.

For my small blog with 1-2 comments a month I'm thinking about implementing a small form and include comments manually using front-matter options or a separate comments file. This would make the comments fully static which is big plus. Spam will obviously be the biggest problem, so something like Akismet is necessary.

[0] https://staticman.net/

[1] https://posativ.org/isso/

[2] https://github.com/netlify/gotell

[3] https://mademistakes.com/articles/jekyll-static-comments/