Hi there, welcome to the community. I’m sorry to read that your Mac died.
Does the chromebook recognize the My Passport? If not most likely is because ChromeOS doesn’t support Apple’s partition table and you might need to borrow another Mac to get the information out.
I’m not a chrome OS user, but, have you checked on the internet if there’s a way that you can make a drive formatted for apple to work on ChromeOS? I know there are apps for windows but I dont know if its the same for ChromeOS.