You can install an apps which basically display the WhatsApp webpage like an app, if you use flathub at least

The standard version of Linux mint is with Cinnamon. Desktop environments are basically how your desktop looks. Cinnamon looks similar to Windows, and Mint is newbie friendly, so you will have no problem moving.

A lot of us understand that if you type anything in a computer it is assumed to be on the public record either easily found or through a few hoops to get it.

The problem is that nowadays your medical documentation, banking and other sensitive data is all transferred through a computer. And it should be protected and private.