I used this to great success in 1.9.1 as well, thanks @whitespacekilla!
Additional steps for 1.9.1: the naming of the development build from Unity 2019.2.2 is slightly different (macosx64_development_mono), and you need the UnityPlayer.dylib as well as (or possibly instead of?) the UnityPlayer binary.
Also as noted by others for Linux and Windows, instead of PlayerConnectionConfigFile, this is now an entry in boot.config, which on the Mac app is stored in Contents/Resources/Data/, so:
I tested with both Visual Studio for Mac (with Unity Tools) and JetBrains Rider, and I wa