For documentation purposes: One can turn WhatsApp Web into an Ubuntu Touch webapp using the following Exec line.

Exec=webapp-container --enable-back-forward --store-session-cookies --user-agent-string="Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36" --webappUrlPatterns=* %u

I won’t publish anything to the store because WhatsApp still goes after third-party apps and I don’t want to be responsible for users being blocked. Also WhatsApp Web is a horrible piece of crap.

If you have an Ubuntu Phone and need an Instant Messenger, please use Telegram instead.