I personally use KDE Connect for this, though I haven't tried using it for transferring contacts this way. I will check and see.
Another cross-platform alternative is to use Syncthing that you can use to sync your folder across phone, PC or Mac. Just install it on all the devices where you want to sync your files and then select the folder to sync on one device and share it with the other devices, it will sync your files automatically in a P2P manner from anywhere in the world to all configured devices.