For the Skycale you need SotO or LW Season 4, while for the Griffon you need PoF. The wiki should easily tell you their unlock conditions. Just be aware of that even though they both can fly, they can't just freely fly around, both have their own types of restrictions. the main differences are that the Skyscale is rather slow but can hover in the air, while the Griffon is more difficult to

OP's suggestion is that flying mounts gain endurance when passing through an updraft, not that flying mounts can use the updraft to gain altitude. True, but the animation cancel is the only purpose: as soon as it's been cancelled you're going right into griffon or skyscale.

But the only change made to the base game when PoF was released was to add areas where mounts could not be used so they didn't trivialise some of the jumping puzzles and mini dungeons. They didn't remove any of the things which made it possible to get 100% map completion without mounts.
LWS4, you have to own the entire season though. Also, Im not sure if its possible without owning PoF, perhaps it is, perhaps it isn't. Someone else who knows might wanna answer. The good thing with owning s4, aside from Skyscale, is the rollerbeetle mount, a legendary trinket, and one of the best maps for farming gold/ascended accessories.
I feel that way on the latest Icebrood Saga map too once the squad is in the northern section. Its not just the fact that the default mounts are slower in getting around the map. It's that with a flying mount you are not being attacked (much) by all the enemy mobs you have to move through to get to the next location.
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guild wars 2 flying mounts