Hello @Tom_K,
Just to make sure I’m understanding you right here, you want to change your Core from your Mac Mini to the Nucleus and keep your Mac Mini as a Roon Remote, but leave the Core functionality to the Nucleus?
If that is your intended objective here, I would suggest you take a look at our Migration Docs and ways to Preserve your Edits.
I would also make sure to have regular Backups set in place and properly share your OSX library according to the instructions in this thread (Nucleus+ is visible on network only via USB-Ethernet adapter).
As for connecting the Mac Mini as a Bridge to WiFi, I have not heard of any users do that, so I can’t confirm if it would work but theoretically it is possible, although for best performance I would always suggest keeping the Nucleus hardwired to your router via Ethernet or an unmanaged switch.
Thanks,
Noris