You should be able to see the values of config_autoTimeSourcesPriority by inspecting the file core/res/res/values/config.xml.

To enable GNSS as a time source, you must set config_enableGnssTimeUpdateService to true and add gnss to the list of sources in config_autoTimeSourcesPriority (these can both be done by modifying the config file mentioned above).

Sources:

https://source.android.com/docs/core/connect/time/gnss-time-detection#implement
https://source.android.com/docs/automotive/time/automatic_time_detection#gnss