Proposal update for sound:
To get sound in the Waydroid AppVM or DisposableVM, in the TemplateVM you should install pipewire-qubes (for Qubes-OS 4.2):
apt install pipewire-qubes -y
Note: to avoid a too big default template (and so a bigger attack surface), I cloned d12m-waydroid to d12m-waydroid-sound and added the above package only in d12m-waydroid-sound. So I choose for an AppVM if I want sound or not.