If ChromeOS is supported, you should be fine. ChromeOS is basically Gentoo with Chrome as the UI for everything. This looks more like a "this is what we tested this site on" than "you absolutely need those specs to do what you have to do".
I just used government sites that recommend Internet Explorer 11 just fine on Firefox. Maybe use Chromium for safety and you should be good. Spoof user agent as needed.
E: ugh stupid "hot" algorithm digging stuff from months ago
It is possible to make the website think I am using chrome and windows, but I don't want to get in trouble for cheating. Even if I use degoogle Chromium it still won't allow me because I use Linux.
Some of them will detect if using virtualization. For example http://safeexambrowser.org/ by ETH Zurich
Ironically enough, it is free software https://github.com/SafeExamBrowser
You can figure out the checks and make your own patches to Qemu.
I managed to get mine working.
Edit: SEB now checks for browser integrity so this is no longer relevant.