Skype has also used it for a long time.

Also, aside from the obvious AV chat systems (eg: Jitsi. Zoom, etc.) 'cloud-gaming' platforms such as Google Stadia and Shadow use it.

I've been monitoring and experimenting with webRTC for a few years now and one of the most exciting recent developments has been more or less full support in desktop and mobile browsers (even Safari, which dragged its heels for years)