Python ECDH with Cryptography Problem Public Key

Currently I started working with the cryptography framework on python. I’m trying to build a SSH Suit by my own but I ran into some problem with the library. I’m trying to build my own Elliptic Curve Key Exchange Init Packet (with scapy).

I’m trying to do an Elliptic Curve Diffie-Hellman key exchange with the curve secp256r1. I’m able to generate the key-pair on my client with out any problem. But after I created the public key object im kinda confused how to get the 32-byte public key for exchange via network packets.

my code so far (which doesn’t work for me):
from cryptography.hazmat.primitives import hashes

from cryptography.hazmat.primitives.asymmetric import ec
from cryptography.hazmat.primitives import serilization

curve = SECP256R1()
peer_private_key = ec.generate_private_key(curve)
peer_public_key = peer_private_key.public_key()

peer_public_pkt = peer_public_key.public_bytes(encoding=serilization.Encoding.DER, format=serialization.PublicFormat.SubjectPublicKeyInfo)

But this peer_public_pkt is not 32 Byte long.

Another Problem is when i get like an ECDH Public Key Value via Scapy or Wireshark from a Server via Network i cant translate the value back with

srv_public_key = ec.EllipticCurvePublicKey.from_encoded_point(curve, data_from_wireshark)

I think I’m missing some crucial steps here but I looked at the documentation for two hours and into some older examples on different sites but I can’t find help (or see the solution).

Hopefully you can help me :). If something about my problem is not clear just ask.