Subject of the issue

The functions for getting/setting the GNSS enabling take a variable of type enum sfe_ublox_gnss_ids_e
However, the implementation indicates a little different use with combined values of this type. So if you want to enable GPS and Galileo you would send SFE_UBLOX_GNSS_ID_GPS | SFE_UBLOX_GNSS_ID_GALILEO but this will result in a warning as this combined value is not a member of the enum. So I'd suggest to change the type to int. As the functions check the actual values anyway, it would not matter if illegal combinations are sent.
However, the isGNSSenabled function does check for all values being set in the parameter, but the result only shows if at least one of those values is enabled. I guess that's not meant, as in that case the true value could immediately be returned. Instead, you should return false immediately if one of the values is not set. That way, all values are properly checked for all being activated.

There is no specific board or module required, it's just being based on code review.

Expected behavior

OR combined enum values should be accepted, as code already deals with it
check for being enabled should return true only if all OR combined GNSS types are activated

Actual behavior

compiler raises warning/error with OR combination
Check function returns true if at least one type is activated