Function ec2_p256_thumbprint 

pub fn ec2_p256_thumbprint(x: &[u8; 32], y: &[u8; 32]) -> [u8; 32]

COSE key type EC2 (kty 2), curve P-256 (crv 1), from the uncompressed coordinates (RFC 9679 §4.2 requires the uncompressed form).