Make Mac act as Bluetooth headset for PS4
It's possible to use your Mac as a speaker for other Apple devices (e.g. using software to turn your Mac into an Airplay receiver). However, there's no current way to turn it into a Bluetooth speaker for devices such as a PS4. 

I suspect this would be possible in theory, however there probably just isn't the demand. The reason why software exists to turn your Mac into a receiver for other Apple devices is that there is a lot of demand for this, especially from iOS users, so various developers have answered the call over the years.