If no --offer provided, it currently selects the first offer on the list (the most recent one). If TEE kind and resources (disk, memory, storage) in rofl.yaml aren't satisfied with the offer, it should skip to the next one until all resources are satisfied.
Keep in mind that the required storage is the specified resources.storage.size in the manifest + an additional 2GB for the oasis-boot image.
If an offer is explicitly selected, return error, if the resources are not satisfied. Pass -f to override the error.