It has always been my understanding that we’re merely talking about swipe-gestures as an alternative to clicking a button that will be visible regardless.
Going back to the hamburger menu on the left: I don’t know about iOS, but on Android there’s definitely a trend of slide-in menus from the left, always discoverable via a visible hamburger bar.
And the menu tends to be a content-portal.
Note: These all had a visible hamburger icon in the top left corner before I clicked/swiped to reveal the menu.
I think this convention makes a lot of sense for Discourse as well.
Interestingly, none of these has a slide-in, full height menu on the right.