How do Unitarians explain Hebrews 1:10-12? How do Unitarians explain Hebrews 1:10-12?

10 And,
“In the beginning, Lord, you founded the earth,
and the heavens are the work of your hands;
11 they will perish, but you remain;
they will all wear out like clothing;
12 like a cloak you will roll them up,
and like clothing﻿﻿ they will be changed.
But you are the same,
and your years will never end.” (NRSV)

These verses are quoted from Psalm 102:25-27, where they are addressed to God, and are applied to Christ in Hebrews 1:10-12
This is a reference to God who created all things aka Gen 1.
It is being re-applied to Jesus. Not to rewrite what was truth, but to add another dimension to it.
We see this pattern with an Immanuel in Is 7:14 and Matt 1:33. The two have no factual connection but the similarities are reapplied with a new focus on the Christ. Many OT passages had fulfilment in their day, but as God designed in to His plan, have much greater significance in Christ.
We can read on to Heb 2:5

5 For He did not subject to angels the world to come, about which we are speaking.

So the context is now evident. Quoting an OT passage and focussing on a new application of it on Christ. This does not undo what was true, but adds the depth God designed in to His word of promise.
Jesus as the firstborn of a new age (Col 1:15,18), which includes all men as brethren (Rom 8:29), is the one who may take the credit for what he accomplished on the cross when he declared, ‘it is finished!’
We can see the initial thread of the message from v1

1 God, after He spoke long ago to the fathers in the prophets in many portions and in many ways, 2 in these last days has spoken to us in His Son, whom He appointed heir of all things, through whom He also made the ages. This last word (ages) is usually translated world or universe which is grossly incorrect. Heb 1:1-2

So Jesus is the figurehead of a new age, even the creator of it as the man given all authority by his Father - and duly deserved!
So the Heb reference in focus is a reiteration of an old glorification of God, now being shared with His triumphant son by the writer of Hebrews.
Jesus being made heir is an absurd concept if (as many presume) he made everything to begin with.
https://www.biblicalunitarian.com/verses/hebrews-1-10 For more info.