Paypal Express, Commerce 3.0, more information on Paypal Invoice

Question

Using Craft 3.4.9 and Commerce Pro 3.0.11

What's the best way to get more information onto a Paypal invoice so that I can match Paypal data with a Craft Commerce order? Does anyone have some success doing this?

At the very least, I would love to be able to pass the item SKU over into the Paypal invoice. Getting the Order Number from Craft onto a Paypal invoice would also be very useful.

There was this similar question back for Commerce 1: How do I send PayPal the Craft Commerce Order Number?

So in Commerce 3, I think a custom plugin with Event hook needs to be used, correct? https://docs.craftcms.com/commerce/api/v3/craft-commerce-services-payments.html#events

probably using the EVENT_BEFORE_PROCESS_PAYMENT event?

But Paypal is javascript based, so looking at the paymentForm.js file, there is the code:

// Copy over all the data to simulate a form being submitted
var postData = {};
var $formElements = $form.find('input[type=hidden]');

for (var i = 0; i < $formElements.length; i++) {
  if ($formElements[i].name === 'action') {
      continue;
  }
  postData[$formElements[i].name] = $formElements.get(i).value;
}

So can I pass acceptable Paypal express items as hidden inputs? It doesn't seem to work.

If I look at: https://developer.paypal.com/docs/archive/checkout/integrate/#2-set-up-a-payment it list there are possible variables which I tried to submit like:

<input type="hidden" name="invoice_number" value="{{ cart.id }}" />
<input type="hidden" name="description" value="{{ cart.id }}" />
<input type="hidden" name="soft_descriptor" value="{{ cart.id }}" />
<input type="hidden" name="note_to_payer" value="{{ cart.id }}" />

But that didn't seem to do anything.

Suggestions?