What's the best practice to "scale down" in a "dev" stack? For a project, we have "prod" and "dev" stack. For "dev", we may want much less full fledged infrastructure compared to "prod". Any suggestion on how to manage that with Pulumi?

you’d really set this on the stack configuration side. do you have any specific examples?

For example, I have "infra-prod" and "infra-dev" accounts. I use Pulumi to create ECR repositories. In prod, we may want 50 repositories. In dev, 2 - 3 is likely good enough. But given they share the same code, they will both end up with 50 repos

+1 to what @billowy-army-68599 said. If you parameterize things like the number of repositories, you can supply values in the stack configuration.

It's not just a number. Each repository has name and other configurations (e.g. immutability setting). Would you recommend put these in the stack config file, or have these in the Python code?

Sorry, I used the number of repositories just as one example; you could certainly extend that to include anything that might need to be set on a per-stack basis.