🟢 How does GSE currently work
TWW’s GSE changes require that you keybind a GSE sequence. This has the consequence that when you get into a vehicle you may have unbound the vehicle controls. Store the original keybind and put it back in case it is needed.

there is an event for vehicles need to figure out what is needed for Skyriding.
https://warcraft.wiki.gg/wiki/UNIT_ENTERING_VEHICLE

https://github.com/BigWigsMods/WoWUI/blob/live/AddOns/Blizzard_Tutorials/Blizzard_Tutorials_Dragonriding.lua#L32

coupled with some of the functions used in https://github.com/BigWigsMods/WoWUI/blob/live/AddOns/Blizzard_ActionBarController/Mainline/ActionBarController.lua#L135

Looks like watching https://warcraft.wiki.gg/wiki/UPDATE_BONUS_ACTIONBAR with this code might be the trick

the skyriding widget itself is (in DF at least) a bit janky but there's PLAYER_IS_GLIDING_CHANGED for actual flight and PLAYER_CAN_GLIDE_CHANGED for being on a skyriding mount

basically if HasBonusActionBar() and GetActionBarPage() == 1 and GetBonusBarIndex() == 11 then

The risk with skyriding is that if combat starts I can rebind the sequence

https://github.com/BigWigsMods/WoWUI/blob/live/AddOns/Blizzard_FrameXML/RestrictedEnvironment.lua#L90

IsFlying() and IsAdvancedFlyableArea() would also suffice

have the button itself SetOverrideBindingClick()

The other suggestions is to add in

/click [vehicleui][possessbar][overridebar] ActionButton2
/stopmacro [vehicleui][possessbar][overridebar]
<Rest of the macro here>