How to get theme’s info from wordpress.org/themes using api.wordpress.org?

by

If you’re in the admin site you can use themes_api()

$info = themes_api( 'theme_information', [ 'slug' => 'twentyten' ] );
echo esc_textarea( $info->sections['description'] );

but that’s plain text, not HTML. The API request it generates is

https://api.wordpress.org/themes/info/1.2/?action=theme_information&request%5Bslug%5D=twentyten&request%5Blocale%5D=en_US&request%5Bwp_version%5D=5.3.2

You can see the parameters in there as multiple URL-encoded request[key] parameters.