I other words, and more generic, how can and should we handle projects that depends on resources managed in other projects? The case above may be specific because indeed in the Lambda project i need to modify the SQS resource (event mapping)

I don't think it's necessarily wise to mix resources between projects/stacks.. or at least if you do, you should never modify the parts under control by another stack. For instance it's perfectly fine to have one stack set up infrastructure like networking, storage, kubernetes, vms, databases, etc - and then another stack manage the contents of kubernetes, access to the database etc. but modifying the database configuration from the second stack isn't really the right approach

Yes, since the lambdas are based on SQS events, i think it's impossible for the lambdas project to not modify an already defined SQS (on another project). Thanks for the reply!

One thing you can consider though.. you can output enough information about the SQS from your first project that your second project can "pick up" where it left off

Not easily infered by the API, but i think this helps connecting to existent infrastructure without having to deal with ownership: https://www.pulumi.com/blog/easy-serverless-apps-and-infrastructure-real-events-real-code/#connect-to-an-existing-resource