Rather than layering the Samba service on Fedora Atomic, shares can be run in a Container. In order to provide relevant examples, this document will imagine a scenario where a backup drive attached to a Fedora IOT device is being shared over the network so that a Fedora Silverblue desktop can use it to store backups taken with a local utility such as Pika Backup, however this should work with for other distros (Atomic or otherwise) as well. The container engine is assumed to be Podman as this comes with Fedora Atomic, but should also work with Docker.
PROCEED AT YOUR OWN RISK
These are the specific instructions that worked for me on an Acer Chromebook Spin 13 and Ultramarine Linux. For more generalised usage, see the source document.
This method requires a raw image not an ISO. There is a method using an ISO in the source material but I haven't tested it.