[nico]

As mentioned in other comments, this is just a concept, they haven’t built it

But it’s a pretty cool concept. Video here:

https://m.youtube.com/watch?v=Q8TUTp0_D-I

[falcor84]

The mounts in the Horizon games on PlayStation are even better as a concept, as they let you actually try it on. And they're probably as close to implementation as this.

https://horizon.fandom.com/wiki/Category:Mountable