Except Akka in Java and for the entirety of Erlang and its children Elixir and Gleam. You obviously can scale those to multiple systems, but they provide a lot of benefit in local single process scenarios too imo.
Things like data pipelines, and games etc etc.
I've worked on a number of systems that used Akka in a non-distributed way and it was always an overengineered approach that made the system more complex for no benefit.
If I'm not mistaken ROOM (ObjecTime, Rational Rose RealTime) was also heavily based on it. I worked in a company that developed real time software for printing machines with it and liked it a lot.