I recently had the experience of testing printing on ChromeOS.
What I learned is that , what I did in ChromeOS, would probably also work on LibreELEC!
SHO 'NUFF!
Today I tested and yes it does work.
This was all on x86_64 so I can not speak for other platforms. Might be interesting to test on others!
What you need:
An IPP or CUPS printer. Many network printters are IPP already , you may need to enable it. CUPS can run on MacOSX, Raspberry PI or other linux, making most any printer IPP
Chrome Browser addon in LibreELEC from here
IPP / CUPS printing for Chrome & Chromebooks - Chrome Web Store (open this from Chrome in LibreELEC)
After install CUPS IPP addon in Chrome on LibreELEC
Configure the printer in the CUPS/IPP addon
My cups address looks like this
http://raspberrypi.local:631/printers/samsung_ml-1670_series
you will need the entire address and path
delete any sample or unused printers from CUPS/IPP addon
Now when printing from chrome, select CUPS/IPP Printer, and away you go!
UPDATE
Fow printing to a WIndows shared printer you can try this:
UniPrint Mint Beta for Chromebooks - Chrome Web Store
I have not tested it
Mark