If you set up the static site generator as a CI/CD action in you favorite git provider, can work with both hosted GitHub, GitLab, etc. or self hosted Forgejo [1], you have both version control for your blog as well as an automatic way of publishing.

Sure, the UX is not that great as with a dedicated interface like substack, but building a Hugo site is really just editing markdown files anyway, most mobile git enabled editors should be able to do that.

[1]: https://home.futuretim.io/posts/hugo_build_and_post/