Unfortunately I need to carry on a bit more with this topic due to the users that really dislike the simplified mobile layout. This especially appears to be the case with tablet users in a vertical orientation.
So I guess I’m still a bit confused about exactly what changed, was the 
/ 
toggle just removed from the sidebar? Can that same JS method still be invoked with a custom script or something? Or is there some change to the desktop layout code that will make it no longer adapt responsively to narrower browser widths?
It looks like the browser’s “Desktop site” toggle (tested in Chrome and Firefox on an Android tablet) does force the old layout that used to correspond to Discourse’s own / toggle, and it still adapts responsively without overflowing. But the text seems to be much smaller than I remember it.
I also know how to select for certain width breakpoints i.e. @media screen and (max-width: 1000px) {… but I’m not sure if anything could be done there with CSS overrides?