Doing your own WordPress (or Drupal or…) subscription setup, with an easy e-mail address entry box and call-to-action, should work as well as anything. For blog-specifically there's Ghost and Bear Blog https://bearblog.dev/ (and others, but those i know have e-mail subscription).
Your best bet, though, is likely WriteFreely, https://writefreely.org/ – allows subscribing by e-mail *or* the fediverse (which Drupal and i think WordPress can do too but that takes work).