We are currently using the "Custom User Lookup" feature, to integrate user data from custom source.
In similar way, it would be useful to have a "Ticket User Lookup" feature, with an URL that can receive some ticket data and output custom data in JSON format, exactly like "custom user lookup" feature.
The ticket data passed to the URL could be the same used in "Send HTTP request" automation rule: "you can use "#subject#", "#url#", "#from#" and "#ticketId#" substitutes to include the ticket subject/link/submitter"