Not that I'm aware of, never even knew it was ever a requirement. I've only used the android client and the browser client. For whatever reason they don't really communicate the browser is out there for use. It's chat.beeper.com for anyone looking.
It may not fit your exact needs, but my solution to WhatsApp and fb messenger is to bridge them with a beeper account. Of course you lose the calling ability, but if you're not using it for calls it is a good enough solution. The other caveat (at least with fb messenger) is you still need to check on your actual account if you get any legit messages from someone not on your list.
Not that I'm aware of, never even knew it was ever a requirement. I've only used the android client and the browser client. For whatever reason they don't really communicate the browser is out there for use. It's chat.beeper.com for anyone looking.