Perhaps a strange question. Today there is a large selection of so-called Internet radio with the ability to receive stations over wi-fi in the local network. Is there any such radio that can play Roon or Arc. Does anyone know?
It depends on how you define an internet radio. I think of it as a tabletop or portable device with built-in speaker, capable of connecting to the internet and playing an audio stream from an online radio station. Basically a streamer with integrated speaker, and to play Roon it would also need to be Roon Ready. The Naim Mu-So comes to mind, and there must be others.
Many connected speakers should also qualify, such as Sonos, the Elac Discovery E3 and others. Although they have minimal controls on the speaker itself and must be operated through a phone or computer app, they have capability to play internet radio and Roon. Remember also that any device that can connect to Roon will also be able to play Roon Live Radio stations.