SonoreUPnP Bridge can run on a small, RasberryPi sized server, or a microRendu or a UltraRendu - all not large components.
Alternatively find a Roon Core server that also runs the SonoreUPnP bridge, so 2 functions I one.
Plus this playback route will be better than converting to S/PDIF and using a digital input on the NDS, as you would with the dCS Bridge or any other Bridge product.
There is an entire thread on this subject here - Simplest way to Roonify NDS