You can easily export the contacts out of Apple Address Books dabases (*.abcddb) files and save them as a vCard files with dedicated programs like AB2CSV.
Convert Apple Address Book database to vCard contacts file.
We have found one software suitable in our database for this conversion.
Apple macOS / Mac OS X software - convert abcddb to vcard on OS X
A small utility used to convert Mac Address Book to CSV format
Convert from abcddb file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.