I figured these out last night. ESRI shapefiles are essentially maps, or more accurately GIS geospatial vector data files. PIC took me a little longer as there are several types of .pic file formats (one of them being a bitmapped image from the days of Lotus 1-2-3), but the plugin in LC is refer to "Pic graphics language diagrams". There isn't much to say about Pic - import it and done - one vector format to another.
ESRI Shapefiles on the other hand almost require a separate manual
, but since they are for a pretty specific purpose, someone using shapefiles probably knows more about them than is needed in the LC User Manual. I submitted a PR...
I did successfully import a shapefile, but it is time consuming. I should add a warning...