So I found that the PhotoSwipe lightbox disables the left right arrows on mobile devices (when it detects them as touch, which can be a hit and miss). But I wonder why. I know the native gallery apps just expect you to swipe all day, but I don't think the arrows have no use. I'd rather tap in one place continuously than go through an album of hundreds of photos by swiping.
Tapping the UI hides all controls letting people swipe without any distraction, so there is that. On this screenshot I enabled them and they don't feel abnormal.