How can I pull a custom report by user and open ticket status?

[Cristina Smith]

Report Criteria

Project

User

Open Ticket Item

[Nic Brough -Adaptavist-]

Use Issues -> Search to find the range of issues you are interested in (probably "project in (x, y, z) and resolution is empty").  Save it once run, and give it a good name

Now head to your dashboard and add a new gadget.  I'd use the two dimensional filter report.  Select your saved filter, and for the axes, project and user.

You don't define which user you want in your question, so you'll need to choose that - assignee, reporter, custom field etc.