Unfortunately, you will need to move the code by hand.
While I've never tried to use aliases to move resources between projects and stacks, the definition of the Alias interface implies that you can, and you won't need to evict the resources from one project and import them into the other. The Alias interface allows you to specify the old resource's project and stack as well as type, name and parent: if project and stack work the same way as the other properties, then Pulumi should move the resource for you just by using the alias opt. You just need to look after the code.