function getDecimalSeparator(locale, options) {
  if (options?.decimalSeparator) {
    return options.decimalSeparator;
  }
  const computedLocale = getLocale(locale);
  const formattedNumber = Intl.NumberFormat(computedLocale, {
    style: 'decimal',
    minimumFractionDigits: 1,
  }).format(1);
  return formattedNumber[1];
}
To get the decimal separator

@param {string} [locale] To override the browser locale
@param {import('../../types/LocalizeMixinTypes.js').FormatNumberOptions} [options]
@returns {string} The separator