I have no knowledge about Spotify and Spotify Connect, but you can install an UPnP server (Asset is recommended, lots of existing posts about it) and then the Nova can stream from there via the “Server” input in the Naim app. (That’s in the mobile app though, no Windows app)
The Qobuz web player in the browser (on Windows) lets you use Chromecast to the Nova, but again no idea about Spotify