So we can build a modal version with Elements that supports all features?

But Stripe removed the modal option from Checkout because features?

A modal with Elements could support all the features that old modal Checkout supports. It would not be able to do all the things that new non-modal Checkout will be able to do in the near future.

You mean SCA-3DS or?

The Stripe 3DS and SCA page says a modal in combination with Elements is fully supported:

Pre-built modal: The Payment Intents API integrates tightly with Stripe.js and Elements to simplify the authentication process. If your Stripe integration uses handleCardPayment or handleCardAction, Stripe.js automatically handles the authentication process—displaying a modal dialog where the customer can provide the requisite information.

This makes it look like we can build a modal version via Elements which fully supports SCA and 3DS through another modal. All on one page.

Also, the Paymentintent docs say we have to set the viewport to mobile on our page so that the UI of Elements can handle 3DS, this makes it also look like it works on our page through a model without redirects. Otherwise Stripe would set the viewport.

Does Elements fully support 3DS and SCA all on our page through modals or not?

https://rrregain.com does this as a service. There are others as well but most do not use your own domain.

Interesting, do you know if they rely on the same principle of using several domains, making it harder to block?

I'm not sure, it uses your own domain, thus www.google-analytics.com becomes yourdomain.com/analytics.js. Not all requests are proxied, only the ones blocked by adblockers.

Taking this further, you could have your server send an event to GA when /index.html is requested, this can even be from tail -f access_log. No one will know GA was requested.

In general, you wouldn't be able to access third-party cookies this way, though.