I assume by ‘make it into the portals of glory’ you are asking if Solomon entered into the kingdom of heaven (or kingdom of God) preached by Jesus Christ.
Matthew 4:17 From that time Jesus began to preach, and to say, Repent: for the kingdom of heaven is at hand.
Mark 1:14... Jesus came into Galilee, preaching the gospel of the kingdom of God, 15 And saying, The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the gospel.
The kingdom of heaven (or kingdom of God) has not yet been established.
It will be established on the earth when Christ returns.
Luke 1:32 He shall be great, and shall be called the Son of the Highest: and the Lord God shall give unto him the throne of his father David: 33 And he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end.
This is the kingdom prophesied through Daniel:
Daniel 2:44 And in the days of these kings shall the God of heaven set up a kingdom, which shall never be destroyed: and the kingdom shall not be left to other people, but it shall break in pieces and consume all these kingdoms, and it shall stand for ever.
Christ will return to judge this world in righteousness.
Acts 17:31 Because he hath appointed a day, in the which he will judge the world in righteousness by that man whom he hath ordained; whereof he hath given assurance unto all men, in that he hath raised him from the dead.
At that time there will be a resurrection and judgment of the dead.
John 5:28... for the hour is coming, in the which all that are in the graves shall hear his voice, 29 And shall come forth; they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation (condemnation).
Until that time Solomon sleeps in the dust; in common with all that have died.
1 Kings 11:43 And Solomon slept with his fathers, and was buried in the city of David his father...
The dead sleep unconsciously.
Ecclesiastes 9:5 For the living know that they shall die: but the dead know not any thing,
Psalms 146:4 His breath goeth forth, he returneth to his earth; in that very day his thoughts perish.
Like David, Solomon awaits the resurrection.
1 Kings 2:10 So David slept with his fathers, and was buried in the city of David.
Acts 2:29 Men and brethren, let me freely speak unto you of the patriarch David, that he is both dead and buried, and his sepulchre is with us unto this day... 34 For David is not ascended into the heavens:
All have died without receiving the promised reward.
Hebrews 11:39 And these all, having obtained a good report through faith, received not the promise: 40 God having provided some better thing for us, that they without us should not be made perfect.
As you rightly point out, Solomon departed from the ways of God in his old age.
1 Kings 11:4 For it came to pass, when Solomon was old, that his wives turned away his heart after other gods: and his heart was not perfect with the LORD his God, as was the heart of David his father.
Nehemiah 13:26 Did not Solomon king of Israel sin by these things? yet among many nations was there no king like him, who was beloved of his God, and God made him king over all Israel: nevertheless even him did outlandish women cause to sin.
Solomon’s judgment will not be made manifest until Christ returns to judge both the living and the dead at his appearing and his kingdom.
Matthew 25:32 And before him shall be gathered all nations: and he shall separate them one from another, as a shepherd divideth his sheep from the goats: 33 And he shall set the sheep on his right hand, but the goats on the left. 34 Then shall the King say unto them on his right hand, Come, ye blessed of my Father, inherit the kingdom prepared for you from the foundation of the world:
At which time we ourselves will be judged.
2 Timothy 4:1 I charge thee therefore before God, and the Lord Jesus Christ, who shall judge the quick (living) and the dead at his appearing and his kingdom;
In conclusion, because scripture is silent upon the matter, speculation on Solomon’s fate can only be speculation.
Rather we are to take warning from the life of Solomon and examine ourselves in the light of the failure of the man whose wisdom exceeded all others (Christ excepted).
1 Corinthians 10:11 Now all these things happened unto them for ensamples: and they are written for our admonition, upon whom the ends of the world are come. 12 Wherefore let him that thinketh he standeth take heed lest he fall.
I hope you have found this helpful.
God bless you,