As much as I hate the cowboy cryptography of it, Telegram could do it. They are a 30 person team and maintain a web version, a first-class Qt desktop app, and native iOS and Android clients.
I would wager that if they wanted to simplify coordination, Flutter would easily kill iOS and Android with one stone, and optionally desktop and web if they so wish, all without a 1GB web wrapper.
Anecdata: I use WhatsApp web daily, and the tab always consumes a bit more than half a gibabyute of RAM. The problem might not be the wrapper, but the sheer waste of resources of the web version.
I would wager that if they wanted to simplify coordination, Flutter would easily kill iOS and Android with one stone, and optionally desktop and web if they so wish, all without a 1GB web wrapper.