One of those things you never thought you needed… and then for some obscure reason you needed someday.
To call an application registered in steam you’ll need the id of the application, the easiest way to get it is just open the store page of said application or game and click the link…
i.e :

By clicking on it it will automatically copy the path to memory
https://store.steampowered.com/app/230410/Warframe
The number 230410 is what we need for our experiment.
To call the application through steam we need to invoke the steam pseudo-url “steam://rungameid/230410” .
Start-Process steam://rungameid/230410
In my case I had to invoke it as an administrator to avoid specific popups (obviously some other application). To do that I used the (in)famous* -Verb RunAs that we’ve come to love and appreciate.
Start-Process powershell -ArgumentList '-NoProfile -Command "Start-Process steam://rungameid/230410"' -Verb RunAs
*Infamous in the fact that when using -Verb you write first the arguments and then the function.