Don't worry I'm sure it will work in 5 or 6 years when they get around to implementing this functionality in some subtly incompatible way on each major desktop environment.
Since its impossible to implement something that works across multiple environments hopefully whichever one does the best job of providing this feature also does a decent job of providing every other feature that previously was able to be provided by any app.
It "works" for me, but my "screen" is virtual - so slack wants to share both monitors as one big screen. So yes, it works, but not for my setup. It isn't useful. Being able to pick which monitor or app to show would make it useful. Being able to share the current app, whatever that is would be awesome.
It has driven me to use google meet - which seems to be more stable and doesn't bog down my system.
