Pull and merge requests
Reading them in the sidebar, without a browser and without editing anything.
The sidebar’s Collaboration group has a section that lists the review
requests for the repository you have open. It is named for the host, so it reads
Pull Requests on GitHub and Merge Requests on GitLab, and it is
there only when the active remote is one of those two.

It is read-only. You can read a request and open it on the provider; you cannot approve, comment or merge from Innesta. That is a deliberate boundary: review is a conversation with people in it, and a client that showed you half of that conversation would be worse than one that sends you to where all of it is.
What you see
A complete, selectable native list — not a scrolling web view — and a three-column detail for the selected request.
Loading happens the first time you enter the section, not when you open the repository, so a repository you never look at requests for never asks the provider anything. There is a manual refresh for when you know something has changed.
Which hosts
GitHub and GitLab. Bitbucket and Azure DevOps are supported for links only — Innesta can build you a URL to a pull request there, and cannot list them.