Yes, nbdev can help with merge conflicts for notebooks [1]. Also checkout,

- GitPlus[2] - JupyterLab extension for git version control

- ReviewNB[3] - For notebooks diffs & commenting

Disclaimer: I built GitPlus & ReviewNB

[1] https://nbdev.fast.ai/#Avoiding-and-handling-git-conflicts

[2] https://github.com/ReviewNB/jupyterlab-gitplus/

[3] https://www.reviewnb.com/