Firefox AddOn that will attempt to detect whether you are on a remote Misskey/Pleroma/Mastodon instance's post, and offer (via an injected button, and a pageAction) to redirect you to your local instance's version of said post.
Configure your instance's base hostname from the ugly options menu available in the Extensions-menu (accessed via Ctrl+Shift+A).
This AddOn is known to work at least on Mastodon version 4.0.2 and Pleroma version 2.4.3
There will be a lot of bugs in how the extension works, it has not been battle tested yet.
This AddOn is licensed under the General Public License GPLv3.