I’ll second this, appear.in is great for lightweight small-group video chats.
I think this might fall under "doesn't solve the same problem at all".
You can share your screen but you cannot share control of your screen. Screenhero was the word on sharing control.
We use appear.in through our paid Slack accounts. I don't know how our admins set is up but we just type /appear in any channel/chat and immediately get a link.
It's a plugin. But it's also trivial to get a URL from the site and paste it in.
In the Slack admin panel you can change the default call provider from slack to others, one of those is appear.in. Doing this will cause the “call” button in the slack app to auto generate a unique link for appear.in and add it to the chat. Works well if your company won’t scrape together for paid version of slack (such as mine).