how many steps (minimum) for a Wynaut egg to hatch?
Wynaut Eggs hatch in 20 Egg cycles.
Generation III 5376 steps
Generation IV 5355 steps
Generation V/VI 5140 steps
Generation VII 5120 steps
Generation VIII/IX 2560 steps
List of Pokémon by breeding attributes (Bulbapedia) Decreasing Egg cycles (Bulbapedia)
It will take you between 5355 - 5609 steps to hatch your wynaut egg, but the amount of time it takes can be halved if you have a Pokemon in your party with the ability flame body or magma armor, such as Ponyta or Slugma :)
Source :http://bulbapedia.bulbagarden.net/wiki/Wynaut_(Pok%C3%A9mon)