Regardless of whether the HomePod supports Apple Lossless (16-bit, 44.1kHz, ALAC) but not Apple Lossless Hi-res (24-bit, 192kHz, ALAC) this entire press release has been a mess.
I don't fully understand why Apple feel the need to announce this at all at this point in time? iOS/iPadOS/tvOS 14.6 and macOS 11.4 has yet to be released which is a requirement for all of this to work. And considering RC of these versions got released yesterday it all might release next week but Dolby Atmos/Spatial Audio and Apple Lossless is still not releasing until June.
Meaning it all requires you to run 14.6 and 11.4 before being able to take advantage of the new features. But it doesn't look like these features will be directly linked to the release of 14.6 and 11.4. Some server-side changes will need to happen in June before it goes live.
So what's the rush? Why not take the time to have all the details ready and perhaps cooperate with some third-parties and provide them with a preview of it all so they can show it to us?
I don't expect Apple Lossless to work with AirPods (regular, Pro or Max) as a result of limitations with Bluetooth. That's common sense at this point in time. But it seems like a bunch of communication is getting confused by the sheer fact that we have so many things going on at once. We have Dolby Atmos/Spatial Audio. We have Apple Lossless. We have Apple Lossless Hi-Res. I suspect things are getting mixed up in the communication.
I have a really hard time seeing any technical limitation for why Apple HomePod and Apple HomePod mini would be incapable of streaming Apple Lossless (not to be confused with Apple Lossless Hi-Res) using AirPlay 2 or by streaming it directly from Apple Music. I can't see any reason why the AirPods Max wouldn't be capable of playing Apple Lossless (not Apple Lossless Hi-Res) using the minijack to Lightning cable.
The reason why the AirPods Max won't be capable of Apple Lossless Hi-Res is most likely due to the transfer going from being digital-to-analogue, then it's going analogue-to-digital on the cable as the AirPods Max only supports digital inputs and then it's going digital-to-analogue on the headphones themselves again. I suspect that the ADC in the cable does not feature support for anything higher than 16-bit, 44.1kHz thus limiting the AirPods Max to "CD-quality" and no "Hi-Res". I can't see any reason why it wouldn't be capable of supporting Apple Lossless. It's only 1411 kbps, there shouldn't be any technical limitations causing the DAC->ADC->DAC transfer to not be able to handle 1411 kbps, 16-bit, 44.1kHz audio.
Unless the ADC in the cable is running some kind of extremely limited ADC and firmware that will only support AAC or stereo PCM and nothing else. If that is the case one has to wonder how Apple didn't think of this with the release of the AirPods Max. But then again, the cable itself is sold separately and could be replaced with a new version adding an updated ADC supporting Apple Lossless. Support for Hi-Res is more difficult as I suspect the DAC within the headphones themselves did never optimise for the use of 24-bit and 192kHz. Heck, CoreAudio within iOS and macOS itself has not been optimised for anything beyond 24-bit, 48kHz. Pushing for anything higher will most likely require fundamental changes to both the operating system and the DAC's Apple is mostly sourcing from Sirrus Logic.