I am looking for an overlay for the Locus Pro with hiking trails.
Hi. Could you be a little more specific? Do you want a map with hiking trails ONLY, to be overlaid atop another map?
I’m not aware of any hiking-trail-only overlay maps, but… Some offline vector map themes have options to enable/disable various features. You could turn off everything but trails. That might work.
If you’re looking for a complete map with trails, those are easy to find.