What is Reddit's opinion of GPS info (plus GLONASS&BeiDou)?

From 3.5 billion Reddit comments

Good choice GPS+GLONASS. Galileo is not as mature as Glonass right now. Good to have Galileo as an option though. If sometimes your watch can't find a solution with GPS or GPS+GLONASS, you can choose GPS+GALILEO.

You can try (if you have patience and time - an hour) some easy to do tests to evaluate the errors for each combination.

1. Go to an "open sky" point. Wait 5 minutes for GPS stabilization (and an improved accuracy). Start an exercise (in the first combination: GPS only) in your watch and stay still in the same "open sky" point for 5-10 minutes (choose x minutes). Then stop the exercise in the watch and see the distance you "walked". You "walked" exactly the errors (in meters) for this snapshot of satellites configuration. Do the next test (for the other combinations: GPS+GLONASS and GPS+GALILEO) immediately - one after the other. In the wait (and still) time you can count the number of GPS, GLONASS and GALILEO available satellites with an app for your phone and correlate them with the errors (see here for a such app). Do a top for the best solution you found (GPS vs GPS+GLONASS vs GPS+GALILEO).
2. Repeat the experiment in a "patched sky" situation (choose a point and look up for obstructed zones: under trees, near buildings, tunnels entries, under the bridges etc). Wait again 5 minutes for GPS stabilization. Start the exercise and stay still for the same x minutes. Repeat foe each combination. Do a top for the best solution you found (GPS vs GPS+GLONASS vs GPS+GALILEO).

Tell us (if you want) about results.

I downloaded this app from the Play Store and it seems to indicate that my XL does.

Download this app and see if it sees any GLONASS satellites.