@nprofile1q... If you've got an idea how ...
I'd prefer without JavaScript although I don't know how to get the messages even with using JS.
There's no active server component either.
So I'd have to establish a cron job that somehow queries parts of the Fediverse and extract messages to generate local copies + backlinks. Doesn't sound reasonable.
What I can think of: adding a button that opens a query for the hashtag on the reader's Mastodon instance somehow... 🤔