Just a couple of thoughts here.
First, right, it’s been my understanding also that Roon have not wanted to integrate services like Amazon Music unless they get the data dumps – and there seems very little reason why Amazon or Apple would want to share those with what to them is a small player like Roon.
However, the level of interest (here in the Roon forums) in Apple High Res seems to be much higher than what Amazon Music prompted: about 800 forum comments on Apple High Res since May 1, 2021, spread across two threads (Apple Music HiFi tier to be announced and Apple Music High Res) vs. about 900 comments on Amazon Music since April 2019 (at Integration of Amazon Music High Resolution).
My impression is that many of the Roon users interested in Apple High Res (myself included) would be really happy just to have the option to play Apple Music through Roon (thus putting Roon’s interface and DSP around Apple Music) – even without the data integration. If that functionality is possible via Apple’s APIs, I wonder if Roon might feel pressure to provide it.
If they don’t, I wonder whether a lot of Roon subscribers who are mostly streaming-only might choose to just switch to Apple music instead of keeping on paying for subscriptions to Roon and Qobuz/Tidal. From what I’ve been reading in the forums, this seems to me a real possibility. I won’t, because I have susbtantial local music, and I have a lifetime sub. But I have the strong impresssion (no data – Roon would know, though) that much of the newer Roon membership is heavily streaming oriented. To such users, the Apple Music value proposition is high as compared to paying for two subscriptions…