Thanks for the useful info on your various pages- there is a lot to read 
Having read this, still unclear if my ACER C720 chromebook is suitable? I may have missed something obvious of course!
HWID is PEPPY-C6B-N7C-A7C ; PEPY-EOL-SCREW
If it is, is there a printable ‘all-in-one’ guide to use?
Many thanks in advance.
I have a C720p and C740. I was able to run ChromeOS flex and linux mint on both of them. You will need to open them up and remove the write protect screw before you can install anything.
close as it gets:
Supports windows, linux, androidx86, and chrome os flex, upgradeable ssd, but fixed ram ( don’t get the 2gb ram variant ) processor is slow af, but a debloated windows or linux with lightweight DE, and careful application installation makes it a good productivity machine (ehm) capable of running gta vc kinda games and 720p youtube, just watch a teardown, re-apply thermal paste (or it’ll clock lower than 1.7Ghz (painful)) and you have something good to give to your kids or do office work
My best option as a linux distro would be kde neon, Q4OS, or windows 10 extremely debloated, I have one that uses ~700-800 mb ram and 3% cpu at idle on such dual core cpus.
Have a nice day