Currently when you want to display a "$" sign or "%" you've got to change the raw data:

 customColumnTypes='[
  {
    "name": "Custom type",
    "customTextProcessing": {
      "changeTextFunc": "(cellText) => `$${Number(cellText.replace(/[^0-9.-]+/g,\"\"))}`",
      "changeStyleFunc": "(cellText) => {
        const moneyNumber = Number(cellText.replace(/[^0-9.-]+/g,\"\"));
        if (moneyNumber < 20) return {backgroundColor: `#ff3232`};
        if (moneyNumber < 100) return {backgroundColor: `#ffff00`};
        return {backgroundColor: `#00ac00`};
      }"
  }}]'

So for example 0.12 should show as 12%. However to get it working you need to change the actual value to 12%. This is bad when when you have to send it back to a server.

Recommendation for a "changeDisplayFunc" function. It would happen after changeTextFunc (for example cleaning data to only display numbers). In the example 0.12:

customColumnTypes='[
  {
    "name": "Percentage",
    "customTextProcessing": {
      "changeDisplayFunc": (cellText) => `${Number(cellText) * 100 }%`
  }}]'