Amazon AWS supports Elastic File System (EFS) as a highly scalable NFS service basically. By installing their new CSI driver in your EKS cluster, this allows a ReadWriteMany storage class. This should satisfy your requirements. You can read more about installing that here.

Note however that EFS performance will not be great. It depends on how the software will want to use it. For example, hosting a database on EFS is not recommended and will probably be too slow. However, hosting shared files on EFS with moderate load and no stringent latency requirements can work well enough!

I am the developer behind airkube.io, which is a managed EKS hosting that runs on AWS spot instances. We tested and had good luck with openebs. This is a good option if you need fairly high performance RWX, you can read more about that option here. The opebebs solution might bring slight complexity though especially if you don't have a dedicated SRE person, or use a managed EKS solution. Another possibly simpler solution, is to use NFS provisioner. This deploys an NFS server and dynamically creates PVs as EKS users deploy PVCs.

Hope that was helpful! Don't hesitate to ping me for more details or hands-on help! Regards