How to send device token as part of the verify MFA requesrt

I am currently using the Authorization API in my SPA to do the login flow. I was trying to use similar approach as the widget does by passing into the header the Cookie with the DT value.

Unfortunately, the browser is removing that header with the name cookie as it is prohibited name value. My question now if there is another way to that and pass the cookie value in a separate place or if there is a flow for passing the device token as part of the verify MFA passcode endpoint.