Apple Music lossless streaming might not be an option for your AirPods, but they will be for your smart speaker. 9to5Mac reports that Apple has promised lossless support for the HomePod and HomePod mini through a "future software update." The company didn't say when this upgrade would arrive, or whether you'd get features like Dolby Atmos through the original HomePod (which already supports Atmos for videos).
The same support document mentioning HomePod support also noted that you could use the AirPods Max to listen to lossless audio through the Lightning to 3.5mm adapter, although the analog-to-digital conversion in the cable meant you'd still lose some audio fidelity. The Lightning to 3.5mm adapter for the IPhone will enable lossless playback through its 24-bit/48kHz DAC.
Apple can offer lossless through HomePods thanks to the extra bandwidth of WiFi. AirPods and other Bluetooth headphones don't have the capacity, according to Apple.
We wouldn't expect a night-and-day difference in sound quality through HomePods, particularly the HomePod mini — there's only so much a mainstream smart speaker can do in terms of replicating the finest details of a song, even if you set up a stereo pair. If nothing else, though, lossless support will ensure that any audio quality limitations are due to the hardware, not the source material.