Build Number:
Pixel 2 (XL): QQ1A.200105.002
Pixel 3 (XL):
T-Mobile/Google Fi: QQ1A.200105.003
All other carriers: QQ1A.200105.002

Pixel 3a (XL): QQ1A.200105.002

Pixel 4 (XL):
Global: QQ1B.200105.004
Japan / Taiwan: QQ1C.200105.004
Japan (NTT Docomo): QQ1D.200105.002

https://developers.google.com/android/images
https://developers.google.com/android/ota

Android Security Bulletin?January 2020
https://source.android.com/security/bulletin/2020-01-01

Pixel Update Bulletin?December 2019
https://source.android.com/security/bulletin/pixel/2020-01-01
https://support.google.com/pixelphone/thread/24852169