Yes, the Channels app now discovers my proxy as a HD Homerun device and I can stream a channel. But after the first stream it crashes. So first I will try to fix that and report back to this topic.
If I can fix it, you can use TVHeadend as a backend. Which is nice if you don’t have a HD Homerun device or if you have to deal with DRM. TVHeadend has options to decode streams with a smartcard, which is why I use it.