As Matthew mentioned, custom JavaScript is needed for this at the moment.
For your particular case, it can be done as follows.
Create a sibling text field, e.g. 'FormattedCurrency', set as hidden. Then include the following JS
function formatNumberToText(numberFieldId, textFieldId) {
LFForm.onFieldChange(() => {
const raw = LFForm.getFieldValues({ fieldId: numberFieldId });
const formatted =
raw === null || raw === "" || isNaN(+raw)
? ""
: Number(raw).toLocaleString("en-US", { minimumFractionDigits: 2, maximumFractionDigits: 2 });
LFForm.setFieldValues({ fieldId: textFieldId }, formatted);
}, { fieldId: numberFieldId });
}
formatNumberToText(6,8);
Where 6 is is field id of the currency, and 8 is the field Id of the 'FormattedCurrency' single line field. The {/dataset/FormattedCurrency} can be used the rich text.
The toLocaleString options can be modified based on your needs.