Not OP but they're likely using Whatsapp already. I'm a big believer in Signal (I have a monthly contribution set up) but Whatsapp is far more common for most

Not OP but they're likely using Whatsapp already. I'm a big believer in Signal (I have a monthly contribution set up) but Whatsapp is far more common for most people to use. I have convinced my older parents and siblings to all use Signal though, so I consider that a win.