I haven't used a Chromebook before because I've always suspected this kind of malfeasance is inevitable, but I wonder...

Could you just rip out the disk device (nvme/etc) and shove a blank one in there?

As long as you never used the backdoored Google account again, at least you could re-use the device for other purposes (albeit with a different OS most likely). Not optimal I agree, but could that be a viable option?

Also, is it possible to virtualize Chrome OS, feasibly? Might be an option for anyone with the skills to firewall/isolate that malware when usage is compulsory.