A lot of people I know regularly use screen sharing through discord or opentalk. Both for work/productivity and while gaming (watching each other, helping, sharing what people are up to etc).
To get people to switch it sadly should support all features: text, voice, video and sending files/images/gifs/videos.
It's tough.
Well, technically you don't need a domain. An IP is enough. If you don't have your own IP (like a shared host) you'll need to put it in a subdirectory but there is no need to have a domain to put something on the Internet.