Privacy Page: Does it need to be a Page? Also, is a warning an error?

[bkjproductions]

When defining the Privacy Page, why does it specifically have to be a Page content type? It could very well be a Post or another content type. As a Page, it sort of then has to live in the hierarchy of Pages. In many situations, we might want to use a special custom post type that has no hierarchy. Or, we may want to set it as a Post of category "Legal" and then we would have other legal-ish Post content in that same category. Or we could have a pop-up. Or it could be in the footer. And so on--- there are many places a Privacy notice could appear, because, as indicated on the support article about this ​https://wordpress.org/support/article/wordpress-privacy/ "Every website is different." (It would be good to explain somewhere why we have to define a Privacy Page in this manner, anyway--- does it create some sort of XML feed or appear in a META tag in the header or something useful and easy to track for compliance?)

Proposal: Allow any post type to be set as the Privacy Page. Even better: Add a checkbox to indicate "We have implemented some other method of a Privacy Page (such as a popup)."

Also, a slight bug: Going to the Settings: Reading panel, there is a message that warns:
Warning: these pages should not be the same as your Privacy Policy page!
when I have not defined the Privacy Policy page. While that may be an important message, it is curious to see it and was not something that I would consider doing anyway. Interestingly, if I define a Posts page here, that message goes away. (That is, it appears when I have defined both the Homepage and the Posts page.) If you have to keep this warning here for some reason, perhaps make the warning not-red, maybe caution color, if that is possible, and add a link over to the Privacy Policy panel in WP Dashboard.
Suggest to use class

.notice-warning

rather than

.notice-error

since this is not really an error.

[bkjproductions]

Message appearing if you have not defined a Privacy Page as an Error when it is a Warning

[garrett-eclipse]

Thanks for the ticket @bkjproductions.

1. Providing support for alternate post types.

Seems like a nice improvement to me, let's use this ticket to work on that for a future release.
If you need to accomplish this currently the dropdown uses the wp_dropdown_pages which then uses get_pages but it also calls the wp_dropdown_pages filter. So technically to support alternate post types now you can filter the output there when the $parsed_args name is set to page_for_privacy_policy and replace the dropdown options with a list of all posts of any type through using get_posts and your desired post types. The output of that filter function would be the full select with the options you want, following existing code from wp_dropdown_pages.

2. Alternate privacy content location, such as popups or external sites.

This was previously raised as a text field you could input any URL for your policy for an alternate case in #44201. That was closed as wontfix by @johnbillion as there is an existing filter to achieve that with privacy_policy_url;
​https://developer.wordpress.org/reference/hooks/privacy_policy_url/
The GUI part was deemed plugin territory for now but will raise with the team for further discussion.

3. Bug: warning notice shouldn't use error styling.

This was previously reported in #50766 and I'm happy to say was fixed in 5.6 (commit [48906]) which will be going into Beta on the 20th.

Hope that helps with you current implementation and we'll revisit the enhancement request in a future version.