Nether Bird

This creature would be based off of the extinct animal group of terror birds. This ''nether terror'' bird would be a rideable mount that could glide down, making it good for scaling around the high grounds of the nether. It would also be fire and lavaproof, but it would drown in water rather quickly. The best part of these animals is the fact that they can move quite quickly on soulsand, and can be put into nether boats to take them with you.

I imagine these animals being quite the hostile mob, initially. But if you hold a special nether stew made out of hoglin beast meat and warped/crimson mushrooms, perhaps you could change their minds.

If you feed them enough of this, they will become neutral and you can then tame them the way you would tame a horse. You would need a saddle to ride these great dwellers of the nether, but once you do you are very much ready to explore the nether to your hearts content!

(this mob COULD also be a compromise to the people whom really wish to be able to have rideable ostriches in the game, if this is however not a possibility then perhaps this could be a good replacement!)