Addition of NAVIC GPS and SatIQ

Yes, while "all systems" always switches on all systems, SatIQ uses the best GNSS that can be received
The bottom line is that the accuracy should be the same, but SatIQ requires less power.
NAVIC is useless outside India.

Fenix 7 records more accurate (longer) distance when running on trails compared to watches with the previous generation GPS chipset (e. g. Fenix 6 or original Enduro) connected to GPS+Glonass. So your watch is likely more accurate in your group. For me, Fenix 6 was consistently short by about 5% when running on trails. 

But in my experience even Fenix 7 is still slightly short compared to official race distances measured with a wheel.  

Also, All Systems includes Glonass, as well as GPS, Galileo, QZSS, Beidou, and now also NavIC. They all are used at the same time and the receiver in the watch picks the strongest satellites from all available satellites in all systems, not just one system at a time.