I've tried ULS (personal position) on mobile and I think that some browsers work better than others, but overall it's usable. (The tests were some time ago, I don't remember the details.)
Both the android browser and the Chrome mobile browser keep things rather small, though IIRC Chrome is smaller, always showing the full width of the page:
After a click, Chrome mobile offers a zoom area for the clicked region, hence misclicking is nearly impossible:
Once opened, the selector is shown in full width and hence quite small:
