However, I initially installed ROCK on a DC3217IYE, which is a 2nd Gen NUC running Ivy Bridge i3 CPU with 8GB RAM and 240GB SATA SSD. This NUC ran ROCK and my Roon Core library fine, at the time.
So the D5420WYKH with an i5 Haswell CPU, 10GB and 240GB SATA SSD should be fine, probably equivalent to a Rev A Nucleus, so good for up to 100K tracks, with a couple of endpoints and limited use of DSP.
See the CPU Performance comparison table I posted here Intel NUC - Roon Rock - only for TIDAL - #8 by simon_pepper
I also had to hand a NUC5i3MYHE, which is Maple Canyon i3, also with 8GB and 240GB SATA SSD. Which was the same as the Rev A Nucleus - this served as my ROCK server from then, 2017 to just earlier this year.
The DC3217IYE was passed out to a friend, for whom it still serves as their Roon Core.
I have also built several NUC5i3MYHE-based ROCK servers, for other friends, all of which are serving perfectly their Roon libraries. I also have a couple of NUC5i3MYHE units as backup servers.
I did make a move to a NUC7i7DNKE (quad-core Kaby Lake-R (Dawson Canyon) i7 CPU) with 16GB and 256GB NVMe PCI SSD drive (the same board as the Rev B Nucleus+), as my library approaches the 100k track point, but other than faster audio analysis scanning, I have not noticed a difference between the NUC5i3 and the NUC7i7