Hi @Steven_Radetsky,
Thank you for your post and for your patience. To answer your original question directly, any iOS device made in recent years (capable of operating with iOS 11+) will be able to connect without issue to any Roon 2.0 RoonServer machine, whether on Nucleus, Windows, Mac, or Linux.
The Nucleus would be the one-stop solution to this issue, but there are advantages to investing in a powerful Mac or Windows computer for the broader utility outside Roon. Any recent M1 or M2 Mac machine will be powerful enough with the library size that you seem to have based on diagnostics.