Various findings on how to start PulseAudio at boot.
https://www.freedesktop.org/wiki/Software/PulseAudio/Documentation/User/SystemWide/ has general information on running PulseAudio systemwide at boot. Those instructions, however, did not seem to actually start the daemon at boot.
sudo chmod 555 /var/run/pulse/.config/pulse/cookie
to get around cookie file/authentication errors.
Modifying /etc/pulse/system.pa with…
load-module module-native-protocol-unix auth-anonymous=1
…seems to help. But, I have no audio when booting into the Pixel GUI.