Uh, no front suspension on your Giant. That makes a big difference. With it locked I can easily do 25 mph, but that’d be a very unpleasant ride - roads here are in rather crappy state, so the front shock needs to be unlocked.
I usually only ride for about 10-20 minutes but I get around on my mountain bike at around 18 mph.
so I’ve been riding the same way old people do other things, slow and sloppy, ~12kmph/7.2mph average, in the snow, all winter, on a fat bike, but things will probably pick up a bit in the spring/summer when I go back to riding a “normal” mountain bike.