oEmbed provider for rich content without using any external tool

[Piyush-Use-Personal]

It is a question

I have been creating a website that lets anyone use components embeddable to their website but the problem is I don't know what I'm doing wrong
For example.
I have created an API and attached it to the link tag for discovery which is getting discovered but for some reason, it is not getting displayed correctly
It is only showing cards for websites like canvas and iframely. Do I need to whitelist my domain from each website or are there any good way to register as provider and using iframes on other website instead of cards
My embeddable URL is https://dashboard-cloner.herokuapp.com/embed.html
any help would be much appreciated
Thanks

[legendarioLegendario]

content://com.android.chrome.FileProvider/downloads/wiredrive.yml