Partial Answer mac power settings script to print

You might be able to use some scripting on a Mac, but a better way is to not print tethered at all, copy the resulting .gcode file to a SD card then plug that into the printer SD card slot. You can use MC to start the print from SD and then unplug the Mac and it will merrily keep printing along.

 

I haven't done it in so long, there are probably others who know it better than I do.

I added an LCD controller right away and it just lets you turn a dial and push a button to select a file to print, couldn't be easier.

 

I have the Full Graphics, but the XXL is actually plug and play.

 

Of the two (I have an assortment of both on my printers, 2 w/XXL and 2/Full Graphics) the XXL is all you really need.
If the Full Graphics nicer? Yes, but you can do everything you need from the XXL unless you have some stringent requirements.
If all you want to do is externally slice a model and then load it on an SD card and print disconnected from a computer, then the XXL will get that job done.

 

Not an endorsement but just the first one that comes up on Amazon Prime
https://smile.amazon.com/BIQU-Displ...10064518&sr=8-5&keywords=smart+lcd+controller
Here is another one from prime slightly cheaper
https://smile.amazon.com/HESAI-Prin...rt+lcd+controller&refinements=p_85:2470955011

They all are made in China, so it generally doesn't matter what the brand name says it is.