Du Pont had been working on trying to manufacture a suitable smokeless powder since the 1860s, along with just about every other powder manufacturer and military in the world.
The first successful smokeless powders, nitrated wood pulps like Schultz's White Powder, came out in the 1870s, but they weren't suitable for use in rifles or handguns, only low-pressure shotshell loads.
Paul Vieille cracked the smokeless question in the 1880s, and that fact was known world wide when Vieille received a very public award from French Academy of Science in 1889. By that time Germany and Austria had both cracked the question.
Du Pont for a time considered licensing manufacture of the German powder Ballistite, developed by Alfred Nobel, and also a Belgian powder (Wettern?), while they continued to work on their own powder.
If a Du Pont traveled to Europe, it was very likely to observe powder manufacturing there and to try to strike a deal to manufacture the new powder.
Winchester first began loading smokeless rifle and handgun powders in 1893, which is what led to the adoption of nickel steel for its future projects, so it makes far more sense that Winchester directed Browning as to the basic specifications of what it wanted in a new sporting rifle.
" John Browning would not allow the 94 to be releases in 94, with out improvements for smokeless powder."
That statement on its own is demonstrably false because Winchester did introduce the Model 1894 in 1894 -- as a blackpowder only rifle and chambered for .38-55 and .32-40. Browning didn't hold back introduction of the rifle.
Nickel steel barrels and smokeless powder cartridges were introduced in the 1895 model year -- when both barrels and powder were available.
