Reordering tabs via touch should work, it was fixed in Firefox 59 (https://bugzilla.mozilla.org/show_bug.cgi?id=1362065). And yes, pinch zoom is not supported (we do text/reflowing zoom, but not mobile-style pinch zoom). It's something that's being worked on but there's a lot of dependencies in order to get it done.

Thanks -- I didn't realize that reordering tabs had been fixed. It only works on the active tab[1] and I guess I've only ever tried moving inactive tabs before. It's not perfect, but so far seems better than in Edge (which allows reordering of inactive tabs but is often rather janky) and Chrome (which has no ability to scroll the tab bar, so tabs quickly get uselessly tiny).

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=1362065#c57

Ah, good point. You should still be able to reorder background tabs using the double-tap-drag gesture (touchdown, touchup, touchdown, touchmove). I haven't tried it recently though.