Add a button that will appear on any community page, post, user, etc that is outside the current instance that says “View On Instance”. When you click on this button, you will be directed to that page on that instance.

For example, if your on the following URL…

https://lemmy.ml/c/fediverse@lemmy.world

And you click the button, you will be taken to…

https://lemmy.world/c/fediverse