Endpoint and remote are different things. Remote is what you use to control Roon, it may or may not even have any sound, but it has requirements for screen size, and OS, because Roon can only write the remote software for some limited number of OS’s and devices. Endpoint is what plays music, it can be anything, running any OS (or no OS at all) as long as the manufacturer implements RAAT protocol.
RS150 (or 250 etc.) are endpoints – they can play music Roon core sends to them, They are not remotes, they can’t be used to control the entire Roon system.