If you're OK with using a third-party and would rather stick to GUI's, Virtru is a very easy solution for email encryption: https://www.virtru.com/
Where by "email encryption" we mean "mail people a link to a service they can register with and then upload messages and file to, so that SMTP is used only to relay links to messages, not the messages themselves, and email is encrypted by dint of TLS connections". That's what most F-500 companies do to solve this problem. It's a more viable approach than direct encryption of PGP. Normal people --- and eventually the…
Sure, but WhatsApp is a totally closed protocol owned by a company (Facebook) known for rampant issues with privacy.
Security professionals have a responsibility to recommend open protocols like Signal that are dedicated to privacy.