Living on the bleeding edge of Gutenberg’s development is not particularly easy for everyone. There is a ton of work and know-how involved with getting everything set up. You have to clone a Git repository, grab pull requests, and run a build process. Non-developers may find themselves facing an overwhelming learning curve. It can be rough for developers who like to keep things simple too.
There are times when it makes sense to simply download a ZIP file, upload it to a WordPress site, and test things out. The most straightforward way is to wait until the development team officially releases an update. You can snag a copy from its WordPress.org plugin page or via the plugins screen in the WordPress admin interface. However, how do you test features between releases?
Gutenberg Times has a page for grabbing a nightly-created ZIP of the plugin. This includes the latest features and bug fixes that have been merged into the project. For users who want to test the plugin and provide feedback to the development team, this is the easiest way to get started.
There are also times when you might want to test changes that are not yet available in the nightly build. Gutenberg currently has 589 pull requests (PRs) — this number changes daily. They are new enhancements and fixes with the potential to be merged into the codebase. Each of these PRs needs a review and feedback. Not all of them will make it in.
For the average user, PR testing is not a reasonable expectation. Even working through Git lingo can be a minefield. However, solutions exist for skipping the intricacies of a developer-only space and hopping into the fray.
One option is Gutenberg.run, a web-based install for testing PRs. The site runs the latest stable release of WordPress and activates a copy of the Gutenberg plugin with the changes from a user-entered PR number.
This is a quick way to test a potential change without spinning up a test install. However, checking out a PR related to Full Site Editing is a no-go. The site has no way to test the site editor, which requires a block-based theme like TT1 Blocks.
Core WordPress contributor Paal Joachim Romdahl outlined a method for testing PRs via a ZIP file. The process is simple, but it is not easy to find if you do not know what you are looking for.
Find a PR. 
Click the Checks tab. 
Build Gutenberg Plugin ZIP
After finding a PR that you want to try, you must click on the “Checks” tab for it on GitHub. Once on the new screen, you can scroll through the left sidebar until you find the “Build Gutenberg Plugin ZIP” link.
From that point, it is a matter of clicking it and downloading the ZIP file — note that it has a ZIP within a ZIP. This download will include the latest version of the plugin with the included PR code applied.
Romdahl has a thorough walkthrough in the following video:
He has also opened a ticket for helping others more easily access a testing ZIP for PRs. The discussion is ongoing. It is currently leaning toward adding an automated comment that outputs a link to the PR build’s ZIP file. This type of exposure should open testing to a wider group of people.
This is a great way for anyone to be able to test out a new feature as it is being made. Some PR’s are just experiments that can take a while to mature while other features will be more quickly merged into Gutenberg. One can get a feel for the direction things are going. Be it through the user interface or other areas.
If you do not see the “Build Gutenberg Plugin ZIP” link in the sidebar in the “Checks” page of a Pull Request (PR). Then create a comment in the Discussion page, and ask if the Build Gutenberg Plugin ZIP can be made available.