Ruby script to import vCard "cell" type phone numbers to a roster: https://gist.github.com/singpolyma/e757d312ef8d4ef0da6a238163eed9cf

Lua script to import from khard vCard store: https://git.2mb.codes/~cmb/commtools/tree/main/item/README.md

Incompatible with new Snikket Servers: Python script to import from CardDAV: https://gitlab.com/djsumdog/dav-xmpp-sync