How do I insert and hide read-only line above specific line in monaco editor?

Question

I need to implement "old school" ruler for monaco editor, which will work similarly to ISPF cols command:

=COLS> ----+----1----+----2----+----3----+----4----+----5----+----6----+----7--
000200 //IEFBR14  EXEC PGM=IEFBR14                                             
=COLS> ----+----1----+----2----+----3----+----4----+----5----+----6----+----7--
000300 //IEFBR14  EXEC PGM=IEFBR14                                             
000400 //IEFBR14  EXEC PGM=IEFBR14                                             
=COLS> ----+----1----+----2----+----3----+----4----+----5----+----6----+----7--
000500 //IEFBR14  EXEC PGM=IEFBR14                                             

The ISPF cols command:

1. The ruler is read-only
2. The ruler is not saved
3. You can place cols to any line(s)

I am aware of rulers: [ a, b, c, ... ] setting which is not very helpful, there are (on mainframe) many specialized (=weird) languages/products, where preset ruler will not help.

I have also found and modified this, but the ruler is placed into the line 1 over the editor text:

var intervalId = setInterval(() => {
    var viewRuler = document.querySelector(".view-ruler");
    if (viewRuler?.style.left) {
        viewRuler.textContent = '----+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8';
        viewRuler.style.width = viewRuler.style.left; // change width to the same as left
        viewRuler.style.left = "0px"; // change left to 0
        clearInterval(intervalId); // clear interval
        console.dir(viewRuler);
    }
}, 1000);