I would suggest having a look at https://confluence.atlassian.com/adminjiracloud/importing-data-from-json-776636779.html to import the project into JIRA.
Once in JIRA, it will be possible to convert the project into a Service Desk.
It might be useful to also open a Service Desk support ticket at https://support.atlassian.com to get some more personalised assistance with the process.
I can't importt from the JSON file. I guess that the JSON file export must contain the correct JIRA Project fields and not the Freshdesk fields.
I have also opened a ticket with :
See import error:
Hello Community members! We’re wrapping up the end of JSM June with an Ask Me Anything (AMA) with the Jira Service Management product team. This is your chance to ask all your ITSM questions to o...
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events