Shopify Apps: Call API Endpoints from Extensions (blocks)

As the title suggest, I’m stuck trying to call some endpoints from the Extension section of the App. I created a section (basically a button) that calls the Create Order endpoint and creates and order before que checkout process (currently I don’t want to do any checkout).

I went to the Partner site and setup the proxy with my Ngrok URL but I’m getting a 404 on a Auth endpoint that it’s executing. Is there any other way of resolving this issue?

Thanks in advance!