When posting content from mastodon, you many find communities you are interested in will have their content behind a content warnings (CWs). With stock Mastodon, this has the side effect of supressing attachments from embedding.
Thus, FxMastodon is FOSS web application that can fix up these embeds similiar to FixTwitter.
To use with any Mastodon (or Mastodon compatible API), you take the URL you want to share, for example...
https://mastodon.social/@Gargron/1...and change it too...
https://fx.zillanlabs.tech/mastodon.social/@Gargron/1...and the server does the rest!
The more instances to pick from, the more the work load can be spread. If you want to host an instance, got Quan Zillan's codeberg for more info: