Another vote for virtualized router! I keep set a core VMs on that host where uptime is the highest priority. I’ve upgraded RAM, downgraded CPU, and eventually switched to an entirely new host with 0 downtime over the past few months. I’d rather not have to wait until everyone else on the network is sleeping before doing any tinkering on the hardware. It’s pretty neat to be streaming some video and then live migrate the router to another physical host with 0 interruption.
Running the hypervisors built in to unraid or truenas are certainly options but proxmox/VMware are just easier. If you’re learning about virtualization, you’re going to find a lot more resources for proxmox/VMware. Conversely the storage capabilities of proxmox/VMware are either severely limited in the case of VMware or just not particularly user friendly for proxmox. By virtualizing your storage OS you can get the best of both worlds for some situations. Sure, there are situations where it’s a bad idea but if you’ve only got one machine and it has plenty of resources it can be very effective.
Heck even if the main function for the NAS is just windows shares, that full blown storage OS is going to give you redundancy, snapshots, and replication. I’d say those are pretty important even for Windows shares.