my device now shows up in your database...
Most intriguingly, it says 2 antennae, even though the Dual-Frequency property is reported as "not supported" and antenna frequencies are reported as L1,L2, so there appears to be the same bug as on the Pixel 5 you mentioned above.
What I can't see though is the csv file with the actual Antenna capabilities, in my gnss_log folder there is only a file called gnss_log_2021_02_12xxxxx.txt and the first lines are:
# Header Description:
#
# Version: v3.9.8 (18085-google), Manufacturer: Google, Model: Pixel 4a (5G), GNSS HW Year: 2020, Platform: 11, API Level: 30
#
# Raw GNSS measurements format:
# Raw,ElapsedRealtimeMillis,TimeNanos,LeapSecond,TimeUncertaintyNanos,FullBiasNanos,BiasNanos,BiasUncertaintyNanos,DriftNanosPerSecond,DriftUncertaintyNanosPerSecond,HardwareClockDiscontinuityCount,Svid,TimeOffsetNanos,State,ReceivedSvTimeNanos,ReceivedSvTimeUncertaintyNanos,Cn0DbHz,PseudorangeRateMetersPerSecond,PseudorangeRateUncertaintyMetersPerSecond,AccumulatedDeltaRangeState,AccumulatedDeltaRangeMeters,AccumulatedDeltaRangeUncertaintyMeters,CarrierFrequencyHz,CarrierCycles,CarrierPhase,CarrierPhaseUncertainty,MultipathIndicator,SnrInDb,ConstellationType,AgcDb,CarrierFrequencyHz
#
# Location fix format:
# Fix,Provider,Latitude,Longitude,Altitude,Speed,Accuracy,(UTC)TimeInMs
#
# Navigation message format:
# Nav,Svid,Type,Status,MessageId,Sub-messageId,Data(Bytes)
#
# NMEA format (for [NMEA sentence] format see
https://www.gpsinformation.org/dale/nmea.htm):
# NMEA,[NMEA sentence],(UTC)TimeInMs
#
# GnssAntennaInfo format (
https://developer.android.com/reference/android/location/GnssAntennaInfo):
# GnssAntennaInfo,CarrierFrequencyMHz,PhaseCenterOffsetXOffsetMm,PhaseCenterOffsetXOffsetUncertaintyMm,PhaseCenterOffsetYOffsetMm,PhaseCenterOffsetYOffsetUncertaintyMm,PhaseCenterOffsetZOffsetMm,PhaseCenterOffsetZOffsetUncertaintyMm,PhaseCenterVariationCorrectionsArray,PhaseCenterVariationCorrectionUncertaintiesArray,PhaseCenterVariationCorrectionsDeltaPhi,PhaseCenterVariationCorrectionsDeltaTheta,SignalGainCorrectionsArray,SignalGainCorrectionUncertaintiesArray,SignalGainCorrectionsDeltaPhi,SignalGainCorrectionsDeltaTheta
followed by NMEA messages in case I switch NMEA logging on... GNSS Antenna Info logging is switched on in settings...
Maybe I'm misunderstanding sth here, and that very last line is already the Antenna Info?