Thanks for the update. Our setup is a little different, unfortunately, and doesn't allow us to use the rebind api: we began with an onprem solution, so our reports are stored as pbix files in our source repo.
We have since added a cloud solution, but both cloud and onprem solutions are sourced off of our repo. This means that the pbix file is a local file which is using an SSAS connection, and not in a power bi workspace using a dataset. Under this scenario, we cannot use the rebind api. We would first have to upload the file to a workspace, which requires a valid dataset to already have been set.
We do have a solution, but it currently involves using some undocumented features. Our only real alternative is to have two versions of each report - one for onprem stored in our repo, and one for cloud stored in a worksapce. This is what we were trying to avoid.