It might be worth adding the option to run code through a DMD with proposed changes in an open PR on the run.dlang.io site. Below dmd-nightly add a dmd-pr, which when selected, adds another input before command-line args to enter a DMD PR number. That should work if the PR passes all checks. (An alternative to adding a new input would be to interpret the first command-line argument as the PR number.)

This would allow the community to quickly try out changes that are not even in the compiler yet.