A lot of this is beyond me and I don’t want to be selling a Roon HW product over something else. But the Nucleus+, probably 2-3 times the price of a comparable computer, does the job perfectly. Moreover, it is a Linux machine that Roon updates it for you (and promises to continue to do so). If you are a computer person, maybe you like messing around between systems that talk to each other in different tongues, but for me, the Nucleus+ is the closest thing to an out-of-box experience you are going to get setting up a network. I built my QNAP NAS, and the configuration was not the simplest thing in the world for me. Another thing about the Nucleus+ and external hard drive combo is that the latter is dirt cheap. Buy two or three HDs. Every month or so, I back up one and take it offsite to my office. That is a true backup in the way that a RAID configuration isn’t – it will survive even my home burning down. I now use the QNAP mostly for data storage, photos, and the like. If you don’t need instant access, it is quite easy. But for music? The QNAP to music streamer connection through WiFi just isn’t fast enough.
I use the Synology DS1621+ model with Seagate IronWolf 12TB NAS Internal Hard Drives. There are larger and smaller NAS solutions Synology makes that can be sized according to your needs.
For Synology at least you need one of the + models IIRC - as it required an Intel CPU
I use QNAP HS-264 as roon core. It is a fanless NAS 
Synology 1622+. It just worked.
Synology 1522+ seems to work well so far, but I don’t have it perform any DSP (although it did not seem to struggle when I tried it).
Synology 1815+ 8 slot. Working great with my precious archive on the hard drives, but I use a dedicated intel NUC as the Core.
My setup that I’m very happy with is Synology 1815+ with roon core running on an SSD, I’m using up-sampling and convolution filters. My library has approx. 55k tracks.
GUI is snappy enough and I regularly have two concurrent users in the family