It's not abandoned AFAIK, it's a small team that does consulting and they have to prioritise work for customers. When that coincides with Ling they can make progress. I've heard this from more than one unikernel/LibOS project.

I'm not sure the second part of your question makes sense in the context of LING. It's a complete reimplementation of an Erlang emulator, not a derivative of BEAM.

That said, I've been working recently with Erlang on Rumprun precisely because I didn't want to rely on a totally unknown commodity (LING) in terms of implementation and behavioral semantics at the same time as drastically changing my operational semantics (unikernel deploy).