Many thanks to Amy Snow who posted some of these resources on the Trainer-talk mailing list including a course which she taught which you can watch on Youtube.
ACVREP AND GOOGLE LAUNCH THE CHROMEBOOK ACCESSIBILITY TRAINING PROGRAM
https://www.acvrep.org/newsitem?id=80
Various Chromebook Accessibility Resources
https://atresources.wcbvi.k12.wi.us/resources/chrome-a11y
ChromeVox: From Basics to Mastery – YouTube
https://www.youtube.com/playlist?list=PLOx3a2GKV3ts7mE_zts5Om2smHmZYrPQ5
Chromebooks – A Journey in Productivity | Mystic Access
$39.00
https://www.mysticaccess.com/product/chromebooks-a-journey-in-productivity/
A World Of Chromebooks – Mystic Access Downloads
https://downloads.mysticaccess.com/download/a-world-of-chromebooks/
Podcast Transcript: Mosen At Large episode 155,
https://mosen.org/malp0155transcript/
Note: Many subsequent Mosen at Large podcast episodes cover additional ChromeBook features.
Please note that I am not a ChromeBook user and so I cannot answer any additional questions or provide support.