Just seen this article leading to this github. Builds provided for the main desktop OSes, with potential to port to more fun platforms with enough work. Haven't tried it yet and it sounds like it's not 100% finished, but in a good useable state and it's very nice to see the protocol being tackled in a free...
Chiaki, an open source PlayStation 4 Remote Play client
Chiaki, an open source PlayStation 4 Remote Play client