I looked into this some, and here's my update.
1.) Team workspace is not really usable in Safari browser on a Mac, it only shows your own camera.
I wasn't able to replicate this issue. When using Team Workspaces Safari desktop, I can see video feeds from other browsers, and those browsers can see my Safari feed as well. (Note that you can't access a Team Workspace video in multiple Safari sessions. If I open an Incognito Safari window and access the same Team Workspace, it exits me from video on the original session.)
2.) Using Safari, you also can't select screen to share so you end up with an infinity of the same screens shared.
This is unfortunately a limitation of Safari. Because we could not add a screen selector with Safari, the sharing defaults to the monitor your browser window is on. If you're sharing your screen to other users, you'll simply need to cover the Safari window with what you wish to display. Other attendees will not see the infinity windows unless you do. If you have multiple monitors available, you can simply move your Safari browser window to a different monitor, and it will continue sharing the monitor you started on.
3.) If using Chrome on an iMac, an iPad Pro and an iPhone, I can get video on the iMac (all 3 people), the iPad Pro (all 3 people), but the iPhone doesn't show any video, not even myself.
5) Chrome on iMac seems to work ok, Chrome on Windows seems to work ok (can share screen and video conference) BUT iPad or iPhone do not have the option of screen sharing and have multiple display issues
I can replicate video issues on Chrome iOS and Chrome iPad.
4) If using Chrome I can use the video conferencing and the person who setup the meeting can share their screen but if people are using iPads or iPhones they can't share their screens.
I can confirm that neither iOS nor iPad have options for screensharing. However, this is by design and is a restriction of the device.
I will get the Chrome issues escalated to the development team so they can look into it.