Proxmox

Proxmox is purpose built for running VMs and containers.  There's a reason most people pair it with Kubernetes.

This is in my top three (with OMV and Ubuntu Server) for a server OS and my pick for clusters and scalability.

The biggest limitation is that you're generally going to be running things in either a VM or a container.  So, it doesn't make a great choice for basic/cheap file sharing.

Note that there will be a learning curve to it.  It does some hand holding in how it streamlines certain tasks but it's not going to necessarily be simple.  Even setting up containers can require extra steps due to the nature of how Proxmox handles things.