Get all CSS for a post

How can I get all the needed inline css for a specific post generated by the page builder?

I will send the post data over the REST API and i want to attach the needed css for the post. The global variable

$siteorigin_panels_inline_css;

gives me the needed css for the containers, but i will also need the widget css.

A bad thing about using this global variable is that when i’m listing posts with the rest API each post get CSS for all other posts in the list.
So, what i like to achieve is something more like

get_all_inline_css_for_post($post_id);

Any suggestions?