In Luke, to whom did Pilate send Jesus after learning he was a Galilean?

Answer: Herod

Learning Jesus was under Herod's jurisdiction, Pilate sent him to Herod, who was in Jerusalem at that time.

“When Pilate heard this, he asked if the man was a Galilean. And learning that Jesus was under Herod’s jurisdiction, he sent Him to Herod, who himself was in Jerusalem at that time.”— Luke 23:6-7 (BSB)