Add Gravatar as oembed provider

[burtrw]

Gravatar recently began supporting oembeds to show a profile card. You can preview the card by appending .card to the end of any profile. For example: ​https://gravatar.com/matt.card

Is the service popular enough for core developers to have heard of it before? Is it “mainstream?”

Yes. 75+ million users and growing.

Does this service have an established social media presence?

Yes, via the parent Automattic brand.

Is its oEmbed endpoint clearly established and properly documented? (Sometimes, they are just a developer’s pet project that may not be supported.)

​https://docs.gravatar.com/api/profiles/embedding-profile-card/

Does the oEmbed endpoint work with WordPress’ oEmbed auto-discovery? If not, could it be made to work with additional HTML tags or attributes being added to the allow-list?

Yes.
Does the service make an effort to build relationships with developers, such as through robust APIs?

Yes: ​https://docs.gravatar.com/api/profiles/rest-api/

How old is the service?
~20 years.

Does it have a well-established Wikipedia article? (Seriously.)
​https://en.wikipedia.org/wiki/Gravatar

Has anyone written a WordPress plugin that leverages the service in some way, whether adding it as an oEmbed provider, creating a shortcode, or leveraging other APIs of the service? Do these plugins have any noticeable adoption or traction that would indicate usage and demand?

The Gravatar Enhanced plugin (​https://wordpress.org/plugins/gravatar-enhanced/) supports oembed in WordPress.

https://core.trac.wordpress.org/ticket/62467

Trac ticket:

[desrosj]

Thanks @burtrw, and welcome to Trac!

Moving to 6.8 for consideration.

[johnbillion]

What's the benefit of adding this to the approved list in core if autodiscovery is enabled?