Maybe a silly question but is possible to fake 'create' resources when developing? Let's say I want to tackle this issue https://github.com/pulumi/pulumi/issues/10256 . I would not want to create that many resources, if possible, on my AWS account. What I do is just create resources that does not cost a penny, like a bunch of IAM roles and policies, etc. But want to know if there are alternatives.

If it’s aws resources, you can run LocalStack and point your local service endpoints to the localhost endpoints and create fake resources. Here’s an example of the approach: https://www.pulumi.com/blog/pulumi-and-localstack/ Note that I haven’t personally tested (or even fully read) that post, but I have used Pulumi with LocalStack before and it’s worked reasonably well

LocalStack makes sense.

Or you can leverage mocks in a pure unit testing setup: https://www.pulumi.com/docs/guides/testing/unit/

Or just make resources with something like Random which doesn't create anything that costs

That random package might be quite useful indeed