(Still) Had to use a flag for Dark pages. I see no Collections nor a flag for it. And, for those who thought HTML would linger or could run side-by-side... the suggestion that one would replace the other is & was correct. So, no Collections & no Set aside & no Dark without a flag. Hmmm Hopefully, we can expect things to show, soon. We know from the betas that they should arrive, soon.
I have, also, tested the app icon to Edge when pinned thing. The specific icons are not holding! They are changing/morphing into generic Edge icons. And, here, no exceptions, all (sites) are doing the same.
Yes collections are only available on Dev/Canary and soon on Beta channel.
about that pinning issue you are referring to, just like one of the developers said earlier, it's Not related to Edge. it's related to Windows.
"...The issue is with Windows, not Edge, and we made a fix in all Windows Insider builds 19xxx and higher. That fix hasn't had a chance to be ported back to non-Insider Windows yet (18363 and lower), so it's not surprising if people are still seeing it there, but if you're seeing it on Windows versions that do have the fix, then it means the fix wasn't sufficient. ... "