Memmy on mobile, https://alexandrite.app/ on desktop.

As I heard, they are gonna be nerfed during autumn, in patch 09-23.

Apparently hotfixes are only available for submarines.

See the Lemmy blog:

At the same time, we are seeing lots of requests to implement major new features, such as migration between instances, or combining similar communities. As described above, we are completely overloaded with work, and definitely won’t have time to implement these in the near future. If there is a feature you want to see implemented, you will likely need to work on it yourself, or find someone who can.

https://join-lemmy.org/news/2023-06-17_-_Update_from_Lemmy_after_the_Reddit_blackout