Issues with virt-manager on POWER

Significant video and input lag.
Lag is substantially worse when the guest is of different Endianness than the host.
GUI only supports adding 3 sound card models, none of which work with POWER (presumably because they're all Intel models).
- The unlisted es1370 sound card does work on POWER if you choose it in the XML.
- It looks like the virtio sound card was introduced in QEMU v8.2.0 (which isn't in Debian Bookworm); it probably works with POWER too but isn't tested.
Even if you add a sound card that works, audio doesn't actually play on the host (at least on Debian Bookworm).

Alternatives

virt-gtk avoids lag and has working sound.