Hello, I’m looking for a way to find out all resources not managed by Pulumi on AWS. Any good suggestion? Thank you!

Depending on your motivation, there probably isn't a 100% way to do this. If you're using the classic AWS provider, it'll use Terraform, which doesn't know about every resource type. I'd suggest a robust set of default Tags applied by Pulumi, and then either use Orgs Tag Policies, or simple Billing reports to call out unmanaged resources.

aws-nuke

is also a great tool to cull mismanaged resources.

Thank you Baz, the default tag seems to be a good start point. I’ll look into

aws-nuke

as well. Thanks!