I have never tried it, but you can set up a mautrix-whatsapp bridge.
Any chance that you can convince them to switch to Telegram, Signal or a Matrix client like Element?
Android/AOSP’s ART has some built-in sandboxing (but Android also has a lot more malware than Linux, so pick your poison). You can always access Whatsapp through a web browser at https://web.whatsapp.com, and web browsers are generally designed to isolate web content from your system.