A future update will bring Apple Music's Lossless audio to both the HomePod and HomePod mini. According to a newly published Apple Support document, the speakers won't get the feature at launch. Still, they will get Spatial Audio at launch, a Dolby Atmos feature that offers an immersive, three-dimensional experience that makes it seem like music is all around the listener.
Apple Music Lossless will come in two tiers and will be free for subscribers. The "Standard" Lossless tier has audio up to 48kHz, while the "Hi-Ress Lossless" has audio between 48kHz and 192kHz. The latter requires external equipment like a USB digital-to-analog converter.
Source: MacRumors