Once saved always saved (OSAS) debunked

Ahhhhhh...no. Not "what" but "who".

And the who is "US"...G2248

https://www.blueletterbible.org/lexicon/g2248/kjv/tr/0-1/

Perhaps the question should be, how can one lose something they never had in the first place?

Judas did not believe and therefore never possessed eternal life/salvation.

For Jesus had known from the beginning which of them did not believe and who would betray him. John 6:64b

so to speak of of Judas as saved or not saved is a straw man argument.

There is no argument strawman or otherwise. We are dealing with a fait accompli exactly as OT prophecy and the unequivocal words of Jesus Himself has specified.

Based on what text?

Are you of the mind people have eternal life before they are born?

The bible states the plan of salvation was laid down before the foundation of the world not that people were chosen before the foundation of the world.

Ephesians 1:4

"chosen" - eklegomai aka "elect"

Ephesians 1:4

The elect become so after they are born again.

Actually in Judas' case, the question is whether people are condemned before they are born.

I am not convinced we can speak about "being born again" until after Jesus rose from the dead.

Romans 8:28-30
28 And we know that all things work together for good to those who love God, to those who are the called according to His purpose.
29 For whom He foreknew, He also predestined to be conformed to the image of His Son, that He might be the firstborn among many brethren.
30 Moreover whom He predestined, these He also called; whom He called, these He also justified; and whom He justified, these He also glorified.

I am not convinced we can speak about "being born again" until after Jesus rose from the dead.

Ephesians 1:4

Romans 8:28-30
28 And we know that all things work together for good to those who love God, to those who are the called according to His purpose.
29 For whom He foreknew, He also predestined to be conformed to the image of His Son, that He might be the firstborn among many brethren.
30 Moreover whom He predestined, these He also called; whom He called, these He also justified; and whom He justified, these He also glorified.

If this were so then the sacrifice of Jesus would not have been necessary.

I see that scripture is clear, those who believed God before the resurrection were accredited with righteousness, even though they had not obtained the promise, those after the resurrection were made righteous through the blood of Jesus and obtained the promise. So Jesus after his death descended to those who were in the bosom of Abraham and brought freedom to them.

As well consider Saul, the Spirit would come upon him one minute and he would prophecy, and the next minute Satan would enter him and he would try to kill David.

John 20 makes clear when the apostles were born again into the New Covenant.

22 And when he had said this, He breathed on them and said to them, “Receive the Holy Spirit.

Was Thomas saved? He didn't believe until he saw,

Paul is talking to already saved people telling them what they are destined for now that they are in Christ.