Try this command (you may lose sound on the host when vm is working, depends on the sound card I believe):
incus config set <vm_name> raw.qemu -- "-device intel-hda -device hda-duplex -audio spice"
Try this command (you may lose sound on the host when vm is working, depends on the sound card I believe):
incus config set <vm_name> raw.qemu -- "-device intel-hda -device hda-duplex -audio spice"