pinephone: volume keys do not work in the initramfs

On edge, I'm unable to use volume keys on boot to interact with the initramfs:

• holding Vol Down when booting does not trigger the debug shell as expected

• Holding Vol Up when fsck fails (to boot anyways) doesn't work

  • I can work around this by plugging in a real keyboard and hitting left-shift to continue booting

Is there a driver and/or udev rule missing from the initramfs that enables the vol keys?