As a Roon server the Nucleus would be much better. The J1800 in the Innuos is very under powered for Roon.
As a player the Innuos would be better because of their linear power supplies.
But the Innuos makes a very expensive player especially if you don’t need CD ripping.
I would personally recommend keeping the server and the player separate for many reasons. Get a network to USB player such as our microRendu or one of the other network players out there.
And get a good dedicated Roon server with plenty of CPU power. I would suggest a NUC (i3, or i5 running ROCK), sonicTransporter i5, or a Roon Nucleus.
You will get better sound from having a dedicated player. You can use multiple players and and single server if you have multiple listening areas and you can upgrade your server and players separately.