The program's import function can be launched automatically from another program (Gmail, Google Drive, File Explorer ...) by opening a "vcf" file.
For this launching, filters are implanted in the program to appear in the list of possible programs when you open a "vcf" file . These filters can in principle be for file type or path.
Type of "vcf" files is not standardized and you may find several variants (text/vcard, text/x-vcard ...), for some applications they are classified as text files.
So I tried a filter on the path to show the program for the files with "vcf" extension. Unfortunately, the Android filter analysis function has limitations and does not distinguish the last point preceding extension from the other points in the path. We must put a filter by number of possible points in the path. It is not reasonable to put too many filters, and I limited myself to five filters allowing to have 1-5 points in the paths.
Unfortunately this filter was not sufficient, and I had to add a filter on file type with types "text/vcard" et "text/x-vcard". With this, this program may appear for all text files opening.