Just a small note: I deleted my Microblog.pub instance. I liked this piece of software and it’s a nice single-user alternative to Mastodon, but I don’t need a Fediverse instance anymore. My new fediverse strategy is to use my normal blog to post stuff (you can follow me via @firstname.lastname@example.org and @email@example.com) and Miniflux to follow people (Mastodon offers RSS user feeds).
If you reply to posts or mention my user handle in a public post on Mastodon, I will receive a notification and your reply will appear in the “Interaction” section under the post.
You’re right, I just took another look at the specs and corrected the template and added the “mediaType” attribute and set it to HTML. Now microblog.pub shows the summary correctly (even with rendered HTML), Pleroma shows the content correctly (without markup), but Mastodon shows the raw HTML code of the summary. 🤔
I think I finally got ActivityPub support for this blog working. On Mastodon, you can search for @firstname.lastname@example.org and @email@example.com to follow the English and German blog. You should also be able to search for the URL of any post and reply to it. But remember that it’s only possible for the reply to appear in the “Interactions” if your profile isn’t locked (so your reply is visible to the public).