It's a Tamper/Violentmonkey script that uses a Bluesky app password to take a post written on Twitter and send it to Mastodon and Bluesky without using the Twitter API. It doesn't work in reverse, unfortunately. github.com/59de44955ebd...

GitHub - 59de44955ebd/twitter-to-bsky: Crosspost from Twitter/X to Bluesky and Mastodon directly in the web browser

Crosspost from Twitter/X to Bluesky and Mastodon directly in the web browser - 59de44955ebd/twitter-to-bsky