A while back (~2 years ago) I was considering an alternate approach that did work as a library rather than a framework.
I never fully finished the work on it, as my priorities had to shift unfortunately, but it is possible to write a custom process registry that will do the dehydration/rehydration of processes for you: PersistentGenServer on GitHub and its ElixirForum topic.
Do note that by itself it only tackles the hydration part and not the ‘distributed persistence’ part. But maybe it can provide as useful idea or building block for someone’s project.