Creating keyword based TOC

Thank you all for the suggestions. I decided to write a short script (with a little help from AI, no less!) to just get all indexed topics and build a custom TOC/index.

Here it is – hopefully will help someone:

#target indesign

// Define the paragraph styles
var indexHeadingStyle = "Index Heading";
var indexStyle = "Index";
var titleStyle = "Title";

// Get the active document
var doc = app.activeDocument;

// Prompt the user to select the text frame for the custom table of contents
if (app.selection.length == 1 && app.selection[0].constructor.name == "TextFrame") {
	var tocTextFrame = app.selection[0];
} else {
	alert("Please select a single text frame for the custom table of contents.");
	exit();
}

// Add the title at the beginning with the Title style
tocTextFrame.contents = "Ingredient Index\r";
tocTextFrame.paragraphs[-1].appliedParagraphStyle = doc.paragraphStyles.item(titleStyle);

// Get all index topics
var indexTopics = doc.indexes[0].allTopics;

for (var i = 0; i < indexTopics.length; i++) {
	var topic = indexTopics[i];

	// Add the index topic with the Index Heading style
	tocTextFrame.insertionPoints[-1].contents = topic.name + "\r";
	tocTextFrame.paragraphs[-1].appliedParagraphStyle = doc.paragraphStyles.item(indexHeadingStyle);

	// Get all page references for the topic
	var pageReferences = topic.pageReferences;

	for (var j = 0; j < pageReferences.length; j++) {
		var pageReference = pageReferences[j];
		var page = pageReference.sourceText.parentTextFrames[0].parentPage;

		// Find the first occurrence of the Title style on the page
		var titleText = null;
		var textFrames = page.textFrames;
		for (var k = 0; k < textFrames.length; k++) {
			var textFrame = textFrames[k];
			var paragraphs = textFrame.paragraphs;
			for (var l = 0; l < paragraphs.length; l++) {
				var paragraph = paragraphs[l];
				if (paragraph.appliedParagraphStyle.name == titleStyle) {
					titleText = paragraph.contents.replace(/[\r\n]+/g, ""); // Remove newlines from titleText
					break;
				}
			}
			if (titleText != null) {
				break;
			}
		}

		// If a title was found, add it with the page number in a new line and apply the Index style
		if (titleText != null) {
			var pageEntry = tocTextFrame.insertionPoints[-1].contents = titleText + "\t" + page.name + "\r";
			tocTextFrame.paragraphs[-1].appliedParagraphStyle = doc.paragraphStyles.item(indexStyle);
		}
	}
}

alert("Custom Index created successfully!");