During SymfonyOnline June 2024, Fabien Potencier himself gave a talk about this topic.

The replay of the talk is free to view (requires a registration): https://live.symfony.com/account/replay/video/968

The slides are available here:

https://speakerdeck.com/fabpot/using-some-git-magic-on-the-symfony-mono-repository-6186213e-8ed7-4d47-8c69-d64748ec2ea9?slide=31