From looking at their build scripts, I would try installing ldacBT, as pipewire is compiled against it but has no install depend on it for installation.
LDAC is proprietary, so I wouldn't be surprised if it isn't available on Linux. You can probably use SBC-XQ, though, which is open source and lossless. Try installing pavucontrol and check what codecs it offers you for the headphones.
That's an ethical question, and as such rather difficult to answer. I prefer open source codecs, but you have a headphone designed with LDAC in mind. I don't think you should feel bad about trying to get your money's worth and using LDAC if it suits your needs.