Works really well!
Using Open Stage Control as my OSC app I now have my setlist info writ large before me.
Prev and Next song and mute status shown. Also individual song parts on display. These are all buttons which will select the function when tapped.
I’m not using a browser to acess Open Stage Control as you normally would. I have Yam Display on the iPad to use it as a remote monitor for the Mac. (It’s too old for Sidecar!) I just dragged the session window to the remote display and hit Fullscreen 
Will be experimenting using the Mac ‘headless’ with the iPad for access. If it works, will consider Mac Mini for an upgrade rather than an MBP.
(Of course I expect thermal issues in the test, when running the MBP with the lid shut)