It's easier to turn an OptiPlex into NAS. Actually you could pass-through entire SATA stack as a PCI device into TruNAS running in Proxmox VM so it sees SATA ports natively, with all goodies such as SMART.
That said, I was running the Homelab on effectively a single Unraid hyperconverged NAS/compute layer before then, and that worked wonders for quite a long time. I wouldn't consider Unraid my first choice now, given the advancements in TrueNAS SCALE in the time since I chose it as the solution, but the concept of NAS + Container Orchestrator as hyperconverged homelab today is quite attractive.
Yeah, that's what I was looking at Proxmox (8.x) for recently as well, but it never made it through basic qualification testing. VM migration's would randomly hang forever about 25% of the time. Definitely not a case of bad network interconnect either. :(
I'm using Ryzen 5000 series cpus on all the test gear though, and recently saw a mention that it may have been a known problem that's fixed. But not super keen on wasting more time.
What sort of cpus are your hosts using, and are you using your VMs with Ceph as their storage? :)
That said, I do have a NAS that I can provide both NFS and iSCSI storage to, so I imagine if I run NFS as the backing storage, I shouldn't have to worry about clustered file systems. Each compute does have local storage, but the plan is to provide that via a CSI for workloads that don't need to be highly available or where fault tolerance isn't a concern.
Can proceed with more testing now. :)