It is possible manage with some extension Project Category with sub-category?
No. Catgories don't have any depth.
You might want to try the "profields" addon which can do something like that (but it's not the built-in category field it works with)
Hi Atlassian community, My name is Max and I work on the product integration team at Atlassian. I am pleased to announce the early access program for the Jira Cloud add-in for Outlook. This add-in...
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