David Hanak The wireless and smart speaker Apple HomePod, which lucky people from three countries around the world will be able to pre-order tomorrow, will offer support for the "audiophile" lossless FLAC format. The information appeared in the technical specifications, and it once again confirms previously published information that Apple is primarily targeting the most demanding music listeners with the new product. As Tim Cook himself mentioned several times – HomePod is above all about a great listening experience. Streaming music in a lossless problem will not be easy, however, because a significantly larger volume of information is transmitted and Bluetooth cannot cope with it.
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Dan Pražák If the user wants to stream some FLAC files, he will have to use the new generation of Air Play. Air Play 2 will appear in the new versions of the operating systems iOS 11.3 and macOS 10.12.4, and will be there primarily for the HomePod (but also for streaming different content to several devices at once). If you are not interested in a lossless format, classic formats such as ALAC or others can be streamed in the usual way via Bluetooth.
In addition to the information about the support for FLAC files, a video has appeared on the site where you can see the activation of the HomePod speaker. It will work similarly to wireless AirPods headphones. The speaker pairs with all the devices that you have connected to your iCloud account, so the condition is activation of the Keychain service. When initially setting up the speaker, you choose its location within your home (whether the speaker is in the living room, bedroom, etc.), then you set the language of the Siri assistant. After agreeing to the terms, the speaker is ready for use.
Source: 9to5mac
"If you are not interested in a lossless format, classic formats such as ALAC or others will stream in the usual way via Bluetooth."
ALAC is also lossless. It's just an Apple modified version of FLAC. The audio format itself is the same.