Here is a small Python function using the amazing Python Cryptography module to generate the Tor v3 Onion service authentication services.

from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import x25519
import base64

def generate_tor_v3_keys():
    "Generates public, private keypair"
    private_key = x25519.X25519PrivateKey.generate()
    private_bytes = private_key.private_bytes(
        encoding=serialization.Encoding.Raw	,
        format=serialization.PrivateFormat.Raw,
        encryption_algorithm=serialization.NoEncryption())
    public_key = private_key.public_key()
    public_bytes = public_key.public_bytes(
        encoding=serialization.Encoding.Raw,
        format=serialization.PublicFormat.Raw)
    public = base64.b32encode(public_bytes).replace(b'=', b'') \
                       .decode("utf-8")
    private = base64.b32encode(private_bytes).replace(b'=', b'') \
                        .decode("utf-8")
    return public, private

You can follow my previous blog post to setup an authenticated Onion service.