Resumable upgrade component coverage for SQL Server 2022 failed in-place upgrade recovery

SQL Server 2022 introduces a resumable upgrade capability for certain components during an in-place upgrade, yet Microsoft states that a full instance upgrade still requires backup-based recovery if it fails. The goal is to define the exact scope of components that support resumable upgrade and understand whether this feature can reduce the need for a complete system database restore after a partial failure.

Constraints include the lack of a publicly enumerated component list in the current documentation and the requirement that any recovery must return the instance to its pre-upgrade version and build number. The repair action (setup.exe /ACTION=Repair) only addresses corrupted binaries and does not revert schema changes made to system databases during the upgrade process.

1. Which specific components or features are eligible for resumable upgrade in SQL Server 2022?
2. Can a resumable upgrade be paused and rolled back without uninstalling the instance and restoring master, model, and msdb from pre-upgrade backups?
3. How does resumable upgrade interact with Always On availability group databases during a rolling upgrade scenario?