And Paul's statement of a thorn in his flesh to keep him from becoming conceited because of these exceedingly great revelations is just chopped liver?
On what sound basis do you resist it?
You assert:
And the point here being: Paul testifies that his doctrine did not come from his or any other man's mind, but only from Jesus Christ personally (Galatians 2:11-12).
I think the evidence fairly strongly supports that Paul received true revelation, the nature of which is not clarified explicitly in much detail. But you make a good point that he claimed to have received it personally from Jesus. Still, I don't think that makes him comparable to Muhummad or Joseph Smith (both being persons who were said to have had messages given to them by angels). Here's why I think Paul is different:
[Eph 1:16-21 NKJV] 16 [ I] do not cease to give thanks for you, making mention of you in my prayers: 17 that the God of our Lord Jesus Christ, the Father of glory, may give to you the
spirit of wisdom and revelation in the knowledge of Him, 18 the
eyes of your [kardia/heart/understanding] being enlightened; that you may know what is the hope of His calling, what are the riches of the glory of His inheritance in the saints, 19 and what [is] the exceeding greatness of His power toward us who believe, according to the working of His mighty power 20 which He worked in Christ when
He raised Him from the dead and seated [Him] at His right hand in the heavenly [places], 21 far above all principality and power and might and dominion, and every name that is named, not only in this age but also in that which is to come.
[Rom 10:10 NKJV] 10
For with the [kardia/heart] one believes unto righteousness, and with the mouth confession is made unto salvation.
We see the same elements from above in this passage concerning a transformation:
[Rom 12:2-3 NKJV] 2 And do not be conformed to this world, but
be transformed by the renewing of your mind, that you may prove what [is] that good and acceptable and perfect will of God. 3 For I say,
through the grace given to me, to everyone who is among you, not to think [of himself] more highly than he ought to think, but to think soberly, as
God has dealt to each one a measure of faith.
Paul, in my view, was exercising senses beyond that of the natural man. It's not that anything was handed to or dictated to him, as though he were a mere messenger, but his mind was changed in a way through experience uncommon to the natural man. That being the case, in effect, he was able to reason as from understanding, and not as though he were like a Joseph Smith, who was said to have received messages (as far as I know).
If you're willing to go out on a limb here, there's more:
[Jhn 3:13 NKJV] 13 "No one has ascended to heaven but He who came down from heaven, [that is], the Son of Man who is in heaven.
[Gal 2:20 NKJV] 20 "I have been crucified with Christ;
it is no longer I who live, but Christ lives in me; and the [life] which I now live in the flesh I live by faith in the Son of God, who loved me and gave Himself for me.
[2Co 11:10 NKJV] 10 As
the truth of Christ is in me ...
So, even though it is not explicitly written out for us in one place, we're given reason to believe that he was caught up to the throne of God, and that Jesus came down, providing Paul with that revelation of Himself, personally.
But since John 3:13 was given with the common understanding that Elijah had been caught up to heaven, wouldn't that mean Elijah was the Son of Man if nobody has been caught up to heaven except the Son of Man, who came down? But wait, there's more concerning the Son of Adam:
[1Sa 10:5-7 NKJV] 5 "... And it will happen, when you have come there to the city, that you will meet a group of prophets coming down from the high place with a stringed instrument, a tambourine, a flute, and a harp before them; and they will be prophesying. 6 "Then the Spirit of the LORD will come upon you,
and you will prophesy with them and be turned into another man. 7 "And let it be, when these signs come to you, [that] you do as the occasion demands; for God [is] with you.
See also:
Genesis 1:1 (NKJV)