Honestly I feel like a screenshot of a toot is better than just seeing a Lemmy-formated toot.
Maybe a cross-post feature which generates what the screenshot effectively shows but formatted in html to match mastodon formatting with functioning links that's hosted on the instance the Lemmy community is in to avoid federation issues?
Edit to add: on the other hand I regularly forward the screenshots to friends on other platforms, so I'd either screenshot the thing created to stop screenshots or need a share/download button to create a image because I know my friends ain't interested in clicking a wierd fediverse link to view a 2 sentence joke they may or may not find funny