Even easier on macOS.
Something like this should work:
ifconfig enX inet6 fd42:dead:beef::1 prefixlen 48
Then you can go ahead and transfer with socat to your other machine, even if it's a Linux machine. I tend to use nc but socat will definitely be faster.
Why the deadbeef network one might wonder? It's private space so won't conflict with public addresses.
That being said though, in 99% cases of big files I'll just airdrop the files!