Is there a way to pull Steam usernames?
I havent tried out Steamworks stuff yet but you should be able to use the Steamworks API to get the Username since it can use all the networking capabilities of Steam
Here is Gdevelops Steamworks documentation:
https://wiki.gdevelop.io/gdevelop5/all-features/steamworks/
You can take a look at steams own documentation here:
https://partner.steamgames.com/doc/home