Script to arrange one pathItem per layer

@nutradial this is one way...

/**
 * @file One Item Per Layer 2.js
 *
 * Moves a layer's page items to a new top-level layer,
 * matching properties of the item's original layer.
 *
 * @author m1b
 * @version 2024-12-19
 */
(function () {

    // will only target this layer
    const TARGET_LAYER = 'Layer 2';

    var doc = app.activeDocument,
        items = doc.pageItems;

    // loop over the page items, backwards,
    // moving each to a new layer, which is
    // a copy of the original layer
    for (var i = items.length - 1, item, layer, newLayer; i >= 0; i--) {

        item = items[i];
        layer = getLayer(item);

        if (
            !layer
            || TARGET_LAYER !== layer.name
        )
            continue;

        layer.locked = false;
        layer.visible = true;

        // create the new layer
        newLayer = doc.layers.add();
        newLayer.color = layer.color
        newLayer.locked = layer.locked
        newLayer.name = layer.name
        newLayer.preview = layer.preview
        newLayer.printable = layer.printable
        newLayer.visible = layer.visible

        // move into place
        newLayer.move(layer, ElementPlacement.PLACEAFTER);
        item.move(newLayer, ElementPlacement.PLACEATBEGINNING);

    }

    // remove empty layers
    for (var i = doc.layers.length - 1; i >= 0; i--) {
        if (
            TARGET_LAYER === doc.layers[i].name
            && 0 === doc.layers[i].pageItems.length
        )
            doc.layers[i].remove();
    }

    /**
     * Returns an item's layer.
     * @param {PageItem} item - an Illustrator PageItem.
     * @returns {Layer?}
     */
    function getLayer(item) {

        var layer = item.parent;

        while (
            undefined !== layer
            && layer.hasOwnProperty('parent')
            && 'Document' !== layer.parent.constructor.name
        )
            layer = layer.parent;

        if ('Layer' === layer.constructor.name)
            return layer;

    };

})();