Fenix 5 Plus: GNSS options - GPS + Galileo + GLONASS (7.10 firmware and later)

What's the latest view on GNSS options on the Fenix 5 Plus?

The vast majority of my efforts using my Garmin Fenix 5 Plus are in the 51-67 degrees zone north of the equator (UK + Nordics), which from what I understand suggests that GPS alone is almost never the best option (I believe GPS is best below 45 degrees). Galileo whilst finally up and running is still relatively new and probably has not been optimised yet in the Garmin firmware, but has overall technical improvements over both GPS and GLONASS. Unfortunately Garmin only supports using GPS as a baseline, and then adding in an additional GNSS constellation.

From a technical standpoint, how are other users that like me tend to play in more northern areas find the performance of your fenix 5 plus series watches when selecting the various GNSS options? I suspect in an ideal world, Galileo + GLONASS combined would probably yield the best results for those of us using these watches in higher latitudes, something not possible using the current firmware.