Can I ask for some suggestion or reference on how to structure Pulumi in a mono repo? We have multiple aws accounts. Do we treat each aws account as a Pulumi project, and have each project as one directory?

I just wrote about this today, perhaps this will help? https://leebriggs.co.uk/blog/2023/08/17/structuring-iac.html

Wow that's exactly what I'm looking for! Very well written. One question in your Control Repo example - can requirement.txt and the virtual environment configs be moved to the root? Does Pulumi support that?

Yep it absolutely does, just make sure your SDK dependencies know where to look