Yes, it is.
Or in the fact 10 dBHz difference is 10 times higher power of the signal which means that actual measured Voltage is about 3 times higher (sqrt 10).
Can you confirm that you observe reasonable performance?
I have gone through manual again, may it be I have remembered threshold 20 from some discussion. I have found that manual states
GNSS positioning CN0 (signal to noise ratio) Threshold from 9 till 40 default 15 dB
But may it be, I have spotted somewhere else that four satellites at more than 20 are required to start algorithm…
There are more commands which can tune parameters $PSTMSETTHTRK
(minimal angle and CN0 for tracking), $PSTMSETTHPOS
(minimal angle and CN0 for positioning), $PSTMCFGGNSS
(complete configuration), $PSTMCFGTHGNSS
combined set of the thresholds only.
So it is chance that by tuning these values we can reach fix earlier. But on the other hand position fluctuation was about 20 to 50 meters when I have reached the fix (after paying and long time during walk around and on the top of the hill there) and recorded and processed NMEA message later. So I think that S/N ratio is under level for solid position computation on my Librem 5 piece so lowering the thresholds does not help too much.
I have not found some Teseo-LIV3 specific values but random papers speaks about 40 to 50 dB max for the satellite in zenith. Marek reports list with maximum at 42 from Xiaomi Mi8 phone under the roof of his home. But he expect that roof is light, so it would not be much better outdoor and he report that this phone has extraordinary good GPS block.
So it is question what is the expected range and performance on Librem 5 and what can be tuned etc… But at least, it is necessary to get some clue what is typical what can be easily solved etc…