-I am aware that the levitation potion can only be accessed via commands
I used this command: /give @p potion 1 16385 {CustomPotionEffects:[{Id:25,Amplifier:1,Duration:10000}]}, and found that it gave you a potion that applies the effect, however, the texture is broken.
Potions no longer use data value/damage, just NBT. Changing that to 0 fixes the texture, though there are still other problems with the command.