I recently restored ChromeOS in anticipation of selling it for the pixel 2 upgrade, and I gotta say - ChromeOS and crouton have both come a long way. Ubuntu via crouton handles everything without any tweaking, which was a major problem I had with Wi-Fi on Debian. You can still take advantage of the <10second-to-browser boot time of ChromeOS if you just need to look a few things up real quick.
To take advantage of everything, if you could get ChromeOS to boot in developer mode (ctrl+d at bios screen) and Debian to boot on legacy boot (ctrl+l at bios screen), then you really get the best of all worlds!
Edit: Nevermind it's really not that bad, just replacing the BIOS, that should be fine. I see little risk of "bricking" a machine here, I'm sure I can get Debian running with these instructions and return the product if it doesn't work well enough.