The Virtual URI docs now mention that we can proxy a request as well as forward and redirect it. See: https://docs.magnolia-cms.com/product-docs/Administration/URI-mapping/Virtual-URI-mapping.html#_the_logic_of_virtual_uri_mapping_in_magnolia

However the detailed part does not mention how the proxying works or how to use it.
See: https://docs.magnolia-cms.com/product-docs/Administration/URI-mapping/Virtual-URI-mapping.html#_action_prefixes

Also, the linked text "See the Action prefixes section" uses an upper case A when the correct anchor is in fact `#_action_prefixes`