This is probably a dumb question, but can't you just log into the school's system using normal Chrome (or even Firefox) on a normal computer? This worked for my (very young) children when COVID made them stay home for a while. The school board issued very nice Chromebooks, but we were afraid of them getting broken, so we just logged in at the computer stations they have anyway, no problem.

You could even spin up a VM image with a very basic Linux install in it for further privilege isolation.