Gearset gives you the ability to see the assigned reviewer for open pull requests (PRs) in the pipelines environment the PR is opened against. You will need to assign the reviewers in your source control provider, as per your usual workflow.

You can also find the reviewer in the Recent promotion history tab of your pipeline environment, followed by View all promotion history.

To see which reviewer is assigned to a PR, navigate to Open pull requests > click on the PR to see the reviewer assigned to it.