Editora 0.20.0. Archived, so links from that release keep working. Read the 0.24.0 page →
GitHub: Check Out Pull Request…
github.checkoutPr Pick an open pull request and check out its branch with the gh CLI.
How to run it
Open the command palette (M-x in the Emacs keymap) and search for GitHub: Check Out Pull Request…, then press Enter. It has no default keybinding, but you can bind one in Settings → Keymaps.