This tool helps you solve merge conflicts in Unity scenes and prefabs. It's a spiritual successor to GitMerge for Unity by the same developer.
It's currently around 90% ready, but needs some finishing touches.
The project is maintained on GitLab, so all bug reports, merge/pull requests should go there.
There is a mirror on GitHub for convenience reasons.
Install this package via package manager by following this manual with the project's url:
https://gitlab.com/13pixels/tools/open-unity-merge-tool.git.
Open the tool's window under Tools/Open Unity Merge Tool.
Initially, pick your project's version control system in the settings.
To start merging a conflicted scene or prefab, click on it in the list.