How do Biblical Unitarians, who deny the Son's pre-existence, understand Hebrews 1:2's "through whom He made the universe"?

Hebrews 1:1-2 is > 1 On many past occasions and in many different ways, God spoke to our > fathers through the prophets. 2 But in these last days He has spoken > to us by His Son, whom He appointed heir of all things, and through > whom He made the universe. (Berean Standard Bible) Biblical Unitarians are broadly of a Socinian bent, denying the literal existence of the Son before his conception, and instead holding the Son is wholly human (not dual-natured). Yet Hebrews 1:2 seems to clearly say the Son was the one through whom the universe was made. The universe was made before Jesus' conception. How do Biblical Unitarians explain this?