Dedicated wifi for automation allows me to have devices such as Xiaomi Vaccuum, or security camera not phoning home. OpenWRT with good firewall rules completely isolate my "public" containers/VMs from my lan.
Server was built over time, disk by disk. I'm now aiming to buy only 12TB drives, but I got to sacrifice the first two as parity...
I just love the simplicity of snapraid / mergerfs. Even if I were to loose 3 disks (my setup allows me the loss of 2 disks), I'd only loose data that's on these disks, not the whole array. I lost one drive once, recovery went well and was relatively easy.
I try to keep things separated and I may be running a bit too many containers/vms, but well, I got resources to spare :)
What are too currently using for your OpenWRT router? I just got one of these and I would highly recommend it: https://a.aliexpress.com/_mq4HxaS
Get the N100 barebones version because you can slap an SSD and RAM in there for cheaper and have more selection. It has four 2.5Gb NICs and the internal PCIE slot for a WiFI card if you really want, though I would recommend getting a Ubiquiti AP to go along with it.
You can put OPNsense on it bare metal, or proxmox and then run your network related VMs there instead of your main server. Your choice.
I got a Netgear AC2000 (R6850) for cheap on sale, and it's been working flawlessly so far